doc/manual.html

<!doctype html>
<html>
  <head>
    <title>CodeMirror: User Manual</title>
    <link rel="stylesheet" type="text/css" href="http://fonts.googleapis.com/css?family=Droid+Sans|Droid+Sans:bold"/>
    <link rel="stylesheet" type="text/css" href="docs.css"/>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <style>dl dl {margin: 0;}</style>
  </head>
  <body>

<h1><span class="logo-braces">{ }</span> <a href="http://codemirror.net/">CodeMirror</a></h1>

<pre class="grey">
<img src="baboon.png" class="logo" alt="logo"/>/* User manual and
   reference guide */
</pre>

<div class="clear"><div class="leftbig blk">

    <h2 id="overview">Overview</h2>

    <p>CodeMirror is a code-editor component that can be embedded in
    Web pages. The code library provides <em>only</em> the editor
    component, no accompanying buttons, auto-completion, or other IDE
    functionality. It does provide a rich API on top of which such
    functionality can be straightforwardly implemented. See
    the <a href="#addons">add-ons</a> included in the distribution,
    and
    the <a href="http://www.octolabs.com/javascripts/codemirror-ui/">CodeMirror
    UI</a> project, for reusable implementations of extra features.</p>

    <p>CodeMirror works with language-specific modes. Modes are
    JavaScript programs that help color (and optionally indent) text
    written in a given language. The distribution comes with a few
    modes (see the <code>mode/</code> directory), and it isn't hard
    to <a href="#modeapi">write new ones</a> for other languages.</p>

    <h2 id="usage">Basic Usage</h2>

    <p>The easiest way to use CodeMirror is to simply load the script
    and style sheet found under <code>lib/</code> in the distribution,
    plus a mode script from one of the <code>mode/</code> directories
    and a theme stylesheet from <code>theme/</code>. (See
    also <a href="compress.html">the compression helper</a>.) For
    example:</p>

    <pre>&lt;script src="lib/codemirror.js">&lt;/script>
&lt;link rel="stylesheet" href="../lib/codemirror.css">
&lt;script src="mode/javascript/javascript.js">&lt;/script></pre>

    <p>Having done this, an editor instance can be created like
    this:</p>

    <pre>var myCodeMirror = CodeMirror(document.body);</pre>

    <p>The editor will be appended to the document body, will start
    empty, and will use the mode that we loaded. To have more control
    over the new editor, a configuration object can be passed
    to <code>CodeMirror</code> as a second argument:</p>

    <pre>var myCodeMirror = CodeMirror(document.body, {
  value: "function myScript(){return 100;}\n",
  mode:  "javascript"
});</pre>

    <p>This will initialize the editor with a piece of code already in
    it, and explicitly tell it to use the JavaScript mode (which is
    useful when multiple modes are loaded).
    See <a href="#config">below</a> for a full discussion of the
    configuration options that CodeMirror accepts.</p>

    <p>In cases where you don't want to append the editor to an
    element, and need more control over the way it is inserted, the
    first argument to the <code>CodeMirror</code> function can also
    be a function that, when given a DOM element, inserts it into the
    document somewhere. This could be used to, for example, replace a
    textarea with a real editor:</p>

    <pre>var myCodeMirror = CodeMirror(function(elt) {
  myTextArea.parentNode.replaceChild(elt, myTextArea);
}, {value: myTextArea.value});</pre>

    <p>However, for this use case, which is a common way to use
    CodeMirror, the library provides a much more powerful
    shortcut:</p>

    <pre>var myCodeMirror = CodeMirror.fromTextArea(myTextArea);</pre>

    <p>This will, among other things, ensure that the textarea's value
    is updated when the form (if it is part of a form) is submitted.
    See the <a href="#fromTextArea">API reference</a> for a full
    description of this method.</p>

    <h2 id="config">Configuration</h2>

    <p>Both the <code>CodeMirror</code> function and
    its <code>fromTextArea</code> method take as second (optional)
    argument an object containing configuration options. Any option
    not supplied like this will be taken
    from <code>CodeMirror.defaults</code>, an object containing the
    default options. You can update this object to change the defaults
    on your page.</p>

    <p>Options are not checked in any way, so setting bogus option
    values is bound to lead to odd errors.</p>

    <p>These are the supported options:</p>

    <dl>
      <dt id="option_value"><code>value (string)</code></dt>
      <dd>The starting value of the editor.</dd>

      <dt id="option_mode"><code>mode (string or object)</code></dt>
      <dd>The mode to use. When not given, this will default to the
      first mode that was loaded. It may be a string, which either
      simply names the mode or is
      a <a href="http://en.wikipedia.org/wiki/MIME">MIME</a> type
      associated with the mode. Alternatively, it may be an object
      containing configuration options for the mode, with
      a <code>name</code> property that names the mode (for
      example <code>{name: "javascript", json: true}</code>). The demo
      pages for each mode contain information about what configuration
      parameters the mode supports. You can ask CodeMirror which modes
      and MIME types are loaded with
      the <code>CodeMirror.listModes</code>
      and <code>CodeMirror.listMIMEs</code> functions.</dd>

      <dt id="option_theme"><code>theme (string)</code></dt>
      <dd>The theme to style the editor with. You must make sure the
      CSS file defining the corresponding <code>.cm-s-[name]</code>
      styles is loaded (see
      the <a href="../theme/"><code>theme</code></a> directory in the
      distribution). The default is <code>"default"</code>, for which
      colors are included in <code>codemirror.css</code>. It is
      possible to use multiple theming classes at once—for
      example <code>"foo bar"</code> will assign both
      the <code>cm-s-foo</code> and the <code>cm-s-bar</code> classes
      to the editor.</dd>

      <dt id="option_indentUnit"><code>indentUnit (integer)</code></dt>
      <dd>How many spaces a block (whatever that means in the edited
      language) should be indented. The default is 2.</dd>

      <dt id="option_smartIndent"><code>smartIndent (boolean)</code></dt>
      <dd>Whether to use the context-sensitive indentation that the
      mode provides (or just indent the same as the line before).
      Defaults to true.</dd>

      <dt id="option_tabSize"><code>tabSize (integer)</code></dt>
      <dd>The width of a tab character. Defaults to 4.</dd>

      <dt id="option_indentWithTabs"><code>indentWithTabs (boolean)</code></dt>
      <dd>Whether, when indenting, the first N*<code>tabSize</code>
      spaces should be replaced by N tabs. Default is false.</dd>

      <dt id="option_electricChars"><code>electricChars (boolean)</code></dt>
      <dd>Configures whether the editor should re-indent the current
      line when a character is typed that might change its proper
      indentation (only works if the mode supports indentation).
      Default is true.</dd>

      <dt id="option_autoClearEmptyLines"><code>autoClearEmptyLines (boolean)</code></dt>
      <dd>When turned on (default is off), this will clear
      automatically clear lines consisting only of whitespace when the
      cursor leaves them. This is mostly useful to prevent auto
      indentation from introducing trailing whitespace in a file.</dd>

      <dt id="option_keyMap"><code>keyMap (string)</code></dt>
      <dd>Configures the keymap to use. The default
      is <code>"default"</code>, which is the only keymap defined
      in <code>codemirror.js</code> itself. Extra keymaps are found in
      the <a href="../keymap/"><code>keymap</code></a> directory. See
      the <a href="#keymaps">section on keymaps</a> for more
      information.</dd>

      <dt id="option_extraKeys"><code>extraKeys (object)</code></dt>
      <dd>Can be used to specify extra keybindings for the editor,
      alongside the ones defined
      by <a href="#option_keyMap"><code>keyMap</code></a>. Should be
      either null, or a valid <a href="#keymaps">keymap</a> value.</dd>

      <dt id="option_lineWrapping"><code>lineWrapping (boolean)</code></dt>
      <dd>Whether CodeMirror should scroll or wrap for long lines.
      Defaults to <code>false</code> (scroll).</dd>

      <dt id="option_lineNumbers"><code>lineNumbers (boolean)</code></dt>
      <dd>Whether to show line numbers to the left of the editor.</dd>

      <dt id="option_firstLineNumber"><code>firstLineNumber (integer)</code></dt>
      <dd>At which number to start counting lines. Default is 1.</dd>

      <dt id="option_gutter"><code>gutter (boolean)</code></dt>
      <dd>Can be used to force a 'gutter' (empty space on the left of
      the editor) to be shown even when no line numbers are active.
      This is useful for setting <a href="#setMarker">markers</a>.</dd>

      <dt id="option_fixedGutter"><code>fixedGutter (boolean)</code></dt>
      <dd>When enabled (off by default), this will make the gutter
      stay visible when the document is scrolled horizontally.</dd>

      <dt id="option_readOnly"><code>readOnly (boolean)</code></dt>
      <dd>This disables editing of the editor content by the user. If
      the special value <code>"nocursor"</code> is given (instead of
      simply <code>true</code>), focusing of the editor is also
      disallowed.</dd>

      <dt id="option_onChange"><code>onChange (function)</code></dt>
      <dd>When given, this function will be called every time the
      content of the editor is changed. It will be given the editor
      instance as first argument, and an <code>{from, to, text, next}</code>
      object containing information about the changes
      that occurred as second argument. <code>from</code>
      and <code>to</code> are the positions (in the pre-change
      coordinate system) where the change started and
      ended (for example, it might be <code>{ch:0, line:18}</code> if the
      position is at the beginning of line #19). <code>text</code>
      is an array of strings representing the text that replaced the changed
      range (split by line). If multiple changes happened during a single
      operation, the object will have a <code>next</code> property pointing to
      another change object (which may point to another, etc).</dd>

      <dt id="option_onCursorActivity"><code>onCursorActivity (function)</code></dt>
      <dd>Will be called when the cursor or selection moves, or any
      change is made to the editor content.</dd>

      <dt id="option_onGutterClick"><code>onGutterClick (function)</code></dt>
      <dd>When given, will be called whenever the editor gutter (the
      line-number area) is clicked. Will be given the editor instance
      as first argument, the (zero-based) number of the line that was
      clicked as second argument, and the raw <code>mousedown</code>
      event object as third argument.</dd>

      <dt id="option_onFocus"><code>onFocus, onBlur (function)</code></dt>
      <dd>The given functions will be called whenever the editor is
      focused or unfocused.</dd>

      <dt id="option_onScroll"><code>onScroll (function)</code></dt>
      <dd>When given, will be called whenever the editor is
      scrolled.</dd>

      <dt id="option_onHighlightComplete"><code>onHighlightComplete (function)</code></dt>
      <dd>Whenever the editor's content has been fully highlighted,
      this function (if given) will be called. It'll be given a single
      argument, the editor instance.</dd>

      <dt id="option_onUpdate"><code>onUpdate (function)</code></dt>
      <dd>Will be called whenever CodeMirror updates its DOM display.</dd>

      <dt id="option_matchBrackets"><code>matchBrackets (boolean)</code></dt>
      <dd>Determines whether brackets are matched whenever the cursor
      is moved next to a bracket.</dd>

      <dt id="option_workTime"><code>workTime, workDelay (number)</code></dt>
      <dd>Highlighting is done by a pseudo background-thread that will
      work for <code>workTime</code> milliseconds, and then use
      timeout to sleep for <code>workDelay</code> milliseconds. The
      defaults are 200 and 300, you can change these options to make
      the highlighting more or less aggressive.</dd>

      <dt id="option_pollInterval"><code>pollInterval (number)</code></dt>
      <dd>Indicates how quickly CodeMirror should poll its input
      textarea for changes. Most input is captured by events, but some
      things, like IME input on some browsers, doesn't generate events
      that allow CodeMirror to properly detect it. Thus, it polls.
      Default is 100 milliseconds.</dd>

      <dt id="option_undoDepth"><code>undoDepth (integer)</code></dt>
      <dd>The maximum number of undo levels that the editor stores.
      Defaults to 40.</dd>

      <dt id="option_tabindex"><code>tabindex (integer)</code></dt>
      <dd>The <a href="http://www.w3.org/TR/html401/interact/forms.html#adef-tabindex">tab
      index</a> to assign to the editor. If not given, no tab index
      will be assigned.</dd>

      <dt id="option_autofocus"><code>autofocus (boolean)</code></dt>
      <dd>When set to <code>true</code>, causes the editor to be
      focused after initialization. Default is <code>false</code>.</dd>

      <dt id="option_onKeyEvent"><code>onKeyEvent (function)</code></dt>
      <dd>This provides a rather low-level hook into CodeMirror's key
      handling. If provided, this function will be called on
      every <code>keydown</code>, <code>keyup</code>,
      and <code>keypress</code> event that CodeMirror captures. It
      will be passed two arguments, the editor instance and the key
      event. This key event is pretty much the raw key event, except
      that a <code>stop()</code> method is always added to it. You
      could feed it to, for example, <code>jQuery.Event</code> to
      further normalize it.<br>This function can inspect the key
      event, and handle it if it wants to. It may return true to tell
      CodeMirror to ignore the event. Be wary that, on some browsers,
      stopping a <code>keydown</code> does not stop
      the <code>keypress</code> from firing, whereas on others it
      does. If you respond to an event, you should probably inspect
      its <code>type</code> property and only do something when it
      is <code>keydown</code> (or <code>keypress</code> for actions
      that need character data).</dd>
    </dl>

    <h2 id="keymaps">Keymaps</h2>

    <p>Keymaps are ways to associate keys with functionality. A keymap
    is an object mapping strings that identify the keys to functions
    that implement their functionality.</p>

    <p>Keys are identified either by name or by character.
    The <code>CodeMirror.keyNames</code> object defines names for
    common keys and associates them with their key codes. Examples of
    names defined here are <code>Enter</code>, <code>F5</code>,
    and <code>Q</code>. These can be prefixed
    with <code>Shift-</code>, <code>Cmd-</code>, <code>Ctrl-</code>,
    and <code>Alt-</code> (in that order!) to specify a modifier. So
    for example, <code>Shift-Ctrl-Space</code> would be a valid key
    identifier.</p>

    <p>Alternatively, a character can be specified directly by
    surrounding it in single quotes, for example <code>'$'</code>
    or <code>'q'</code>. Due to limitations in the way browsers fire
    key events, these may not be prefixed with modifiers.</p>

    <p>The <code>CodeMirror.keyMap</code> object associates keymaps
    with names. User code and keymap definitions can assign extra
    properties to this object. Anywhere where a keymap is expected, a
    string can be given, which will be looked up in this object. It
    also contains the <code>"default"</code> keymap holding the
    default bindings.</p>

    <p>The values of properties in keymaps can be either functions of
    a single argument (the CodeMirror instance), or strings. Such
    strings refer to properties of the
    <code>CodeMirror.commands</code> object, which defines a number of
    common commands that are used by the default keybindings, and maps
    them to functions. A key handler function may throw
    <code>CodeMirror.Pass</code> to indicate that it has decided not
    to handle the key, and other handlers (or the default behavior)
    should be given a turn.</p>

    <p>Keys mapped to command names that start with the
    characters <code>"go"</code> (which should be used for
    cursor-movement actions) will be fired even when an
    extra <code>Shift</code> modifier is present (i.e. <code>"Up":
    "goLineUp"</code> matches both up and shift-up). This is used to
    easily implement shift-selection.</p>

    <p>Keymaps can defer to each other by defining
    a <code>fallthrough</code> property. This indicates that when a
    key is not found in the map itself, one or more other maps should
    be searched. It can hold either a single keymap or an array of
    keymaps.</p>

    <p>When a keymap contains a <code>catchall</code> property, the
    handler function under that property will be called for all keys
    dispatched through the keymap.</p>

    <h2 id="styling">Customized Styling</h2>

    <p>Up to a certain extent, CodeMirror's look can be changed by
    modifying style sheet files. The style sheets supplied by modes
    simply provide the colors for that mode, and can be adapted in a
    very straightforward way. To style the editor itself, it is
    possible to alter or override the styles defined
    in <a href="../lib/codemirror.css"><code>codemirror.css</code></a>.</p>

    <p>Some care must be taken there, since a lot of the rules in this
    file are necessary to have CodeMirror function properly. Adjusting
    colors should be safe, of course, and with some care a lot of
    other things can be changed as well. The CSS classes defined in
    this file serve the following roles:</p>

    <dl>
      <dt id="class_CodeMirror"><code>CodeMirror</code></dt>
      <dd>The outer element of the editor. This should be used for
      borders and positioning. Can also be used to set styles that
      should hold for everything inside the editor (such as font
      and font size), or to set a background.</dd>

      <dt id="class_CodeMirror_scroll"><code>CodeMirror-scroll</code></dt>
      <dd>This determines whether the editor scrolls (<code>overflow:
      auto</code> + fixed height). By default, it does. Giving
      this <code>height: auto; overflow: visible;</code> will cause
      the editor to resize to fit its content.</dd>

      <dt id="class_CodeMirror_focused"><code>CodeMirror-focused</code></dt>
      <dd>Whenever the editor is focused, the top element gets this
      class. This is used to hide the cursor and give the selection a
      different color when the editor is not focused.</dd>

      <dt id="class_CodeMirror_gutter"><code>CodeMirror-gutter</code></dt>
      <dd>Use this for giving a background or a border to the editor
      gutter. Don't set any padding here,
      use <code>CodeMirror-gutter-text</code> for that. By default,
      the gutter is 'fluid', meaning it will adjust its width to the
      maximum line number or line marker width. You can also set a
      fixed width if you want.</dd>

      <dt id="class_CodeMirror_gutter_text"><code>CodeMirror-gutter-text</code></dt>
      <dd>Used to style the actual line numbers. For the numbers to
      line up, you must make sure that the font in the gutter is the
      same as the one in the rest of the editor, so you should
      probably only set font style and size in
      the <code>CodeMirror</code> class.</dd>

      <dt id="class_CodeMirror_lines"><code>CodeMirror-lines</code></dt>
      <dd>The visible lines. If this has vertical
      padding, <code>CodeMirror-gutter</code> should have the same
      padding.</dd>

      <dt id="class_CodeMirror_cursor"><code>CodeMirror-cursor</code></dt>
      <dd>The cursor is a block element that is absolutely positioned.
      You can make it look whichever way you want.</dd>

      <dt id="class_CodeMirror_selected"><code>CodeMirror-selected</code></dt>
      <dd>The selection is represented by <code>span</code> elements
      with this class.</dd>

      <dt id="class_CodeMirror_matchingbracket"><code>CodeMirror-matchingbracket</code>,
        <code>CodeMirror-nonmatchingbracket</code></dt>
      <dd>These are used to style matched (or unmatched) brackets.</dd>
    </dl>

    <p>The actual lines, as well as the cursor, are represented
    by <code>pre</code> elements. By default no text styling (such as
    bold) that might change line height is applied. If you do want
    such effects, you'll have to give <code>CodeMirror pre</code> a
    fixed height. Also, you must still take care that character width
    is constant.</p>

    <p>If your page's style sheets do funky things to
    all <code>div</code> or <code>pre</code> elements (you probably
    shouldn't do that), you'll have to define rules to cancel these
    effects out again for elements under the <code>CodeMirror</code>
    class.</p>

    <p>Themes are also simply CSS files, which define colors for
    various syntactic elements. See the files in
    the <a href="../theme/"><code>theme</code></a> directory.</p>

    <h2 id="api">Programming API</h2>

    <p>A lot of CodeMirror features are only available through its API.
    This has the disadvantage that you need to do work to enable them,
    and the advantage that CodeMirror will fit seamlessly into your
    application.</p>

    <p>Whenever points in the document are represented, the API uses
    objects with <code>line</code> and <code>ch</code> properties.
    Both are zero-based. CodeMirror makes sure to 'clip' any positions
    passed by client code so that they fit inside the document, so you
    shouldn't worry too much about sanitizing your coordinates. If you
    give <code>ch</code> a value of <code>null</code>, or don't
    specify it, it will be replaced with the length of the specified
    line.</p>

    <dl>
      <dt id="getValue"><code>getValue() → string</code></dt>
      <dd>Get the current editor content.</dd>
      <dt id="setValue"><code>setValue(string)</code></dt>
      <dd>Set the editor content.</dd>

      <dt id="getSelection"><code>getSelection() → string</code></dt>
      <dd>Get the currently selected code.</dd>
      <dt id="replaceSelection"><code>replaceSelection(string)</code></dt>
      <dd>Replace the selection with the given string.</dd>

      <dt id="focus"><code>focus()</code></dt>
      <dd>Give the editor focus.</dd>
      <dt id="scrollTo"><code>scrollTo(x, y)</code></dt>
      <dd>Scroll the editor to a given (pixel) position. Both
      arguments may be left as <code>null</code>
      or <code>undefined</code> to have no effect.</dd>

      <dt id="setOption"><code>setOption(option, value)</code></dt>
      <dd>Change the configuration of the editor. <code>option</code>
      should the name of an <a href="#config">option</a>,
      and <code>value</code> should be a valid value for that
      option.</dd>
      <dt id="getOption"><code>getOption(option) → value</code></dt>
      <dd>Retrieves the current value of the given option for this
      editor instance.</dd>

      <dt id="cursorCoords"><code>cursorCoords(start, mode) → object</code></dt>
      <dd>Returns an <code>{x, y, yBot}</code> object containing the
      coordinates of the cursor. If <code>mode</code>
      is <code>"local"</code>, they will be relative to the top-left
      corner of the editable document. If it is <code>"page"</code> or
      not given, they are relative to the top-left corner of the
      page. <code>yBot</code> is the coordinate of the bottom of the
      cursor. <code>start</code> is a boolean indicating whether you
      want the start or the end of the selection.</dd>
      <dt id="charCoords"><code>charCoords(pos, mode) → object</code></dt>
      <dd>Like <code>cursorCoords</code>, but returns the position of
      an arbitrary characters. <code>pos</code> should be
      a <code>{line, ch}</code> object.</dd>
      <dt id="coordsChar"><code>coordsChar(object) → pos</code></dt>
      <dd>Given an <code>{x, y}</code> object (in page coordinates),
      returns the <code>{line, ch}</code> position that corresponds to
      it.</dd>

      <dt id="undo"><code>undo()</code></dt>
      <dd>Undo one edit (if any undo events are stored).</dd>
      <dt id="redo"><code>redo()</code></dt>
      <dd>Redo one undone edit.</dd>
      <dt id="historySize"><code>historySize() → object</code></dt>
      <dd>Returns an object with <code>{undo, redo}</code> properties,
      both of which hold integers, indicating the amount of stored
      undo and redo operations.</dd>
      <dt id="clearHistory"><code>clearHistory()</code></dt>
      <dd>Clears the editor's undo history.</dd>

      <dt id="indentLine"><code>indentLine(line, dir)</code></dt>
      <dd>Reset the given line's indentation to the indentation
      prescribed by the mode. If the second argument is given,
      indentation will be increased (if <code>dir</code> is true) or
      decreased (if false) by an <a href="#option_indentUnit">indent
      unit</a> instead.</dd>

      <dt id="getTokenAt"><code>getTokenAt(pos) → object</code></dt>
      <dd>Retrieves information about the token the current mode found
      at the given position (a <code>{line, ch}</code> object). The
      returned object has the following properties:
      <dl>
        <dt><code>start</code></dt><dd>The character (on the given line) at which the token starts.</dd>
        <dt><code>end</code></dt><dd>The character at which the token ends.</dd>
        <dt><code>string</code></dt><dd>The token's string.</dd>
        <dt><code>className</code></dt><dd>The class the mode assigned
        to the token. (Can be null when no class was assigned.)</dd>
        <dt><code>state</code></dt><dd>The mode's state at the end of this token.</dd>
      </dl></dd>

      <dt id="markText"><code>markText(from, to, className) → object</code></dt>
      <dd>Can be used to mark a range of text with a specific CSS
      class name. <code>from</code> and <code>to</code> should
      be <code>{line, ch}</code> objects. The method will return an
      object with two methods, <code>clear()</code>, which removes the
      mark, and <code>find()</code>, which returns a <code>{from,
      to}</code> (both document positions), indicating the current
      position of the marked range.</dd>

      <dt id="setBookmark"><code>setBookmark(pos) → object</code></dt>
      <dd>Inserts a bookmark, a handle that follows the text around it
      as it is being edited, at the given position. A bookmark has two
      methods <code>find()</code> and <code>clear()</code>. The first
      returns the current position of the bookmark, if it is still in
      the document, and the second explicitly removes the
      bookmark.</dd>

      <dt id="findMarksAt"><code>findMarksAt(pos) → array</code></dt>
      <dd>Returns an array of all the bookmarks and marked ranges
      present at the given position.</dd>

      <dt id="setMarker"><code>setMarker(line, text, className) → lineHandle</code></dt>
      <dd>Add a gutter marker for the given line. Gutter markers are
      shown in the line-number area (instead of the number for this
      line). Both <code>text</code> and <code>className</code> are
      optional. Setting <code>text</code> to a Unicode character like
      ● tends to give a nice effect. To put a picture in the gutter,
      set <code>text</code> to a space and <code>className</code> to
      something that sets a background image. If you
      specify <code>text</code>, the given text (which may contain
      HTML) will, by default, replace the line number for that line.
      If this is not what you want, you can include the
      string <code>%N%</code> in the text, which will be replaced by
      the line number.</dd>
      <dt id="clearMarker"><code>clearMarker(line)</code></dt>
      <dd>Clears a marker created
      with <code>setMarker</code>. <code>line</code> can be either a
      number or a handle returned by <code>setMarker</code> (since a
      number may now refer to a different line if something was added
      or deleted).</dd>
      <dt id="setLineClass"><code>setLineClass(line, className, backgroundClassName) → lineHandle</code></dt>
      <dd>Set a CSS class name for the given line. <code>line</code>
      can be a number or a line handle (as returned
      by <code>setMarker</code> or this
      function). <code>className</code> will be used to style the text
      for the line, and <code>backgroundClassName</code> to style its
      background (which lies behind the selection).
      Pass <code>null</code> to clear the classes for a line.</dd>
      <dt id="hideLine"><code>hideLine(line) → lineHandle</code></dt>
      <dd>Hide the given line (either by number or by handle). Hidden
      lines don't show up in the editor, and their numbers are skipped
      when <a href="#option_lineNumbers">line numbers</a> are enabled.
      Deleting a region around them does delete them, and coping a
      region around will include them in the copied text.</dd>
      <dt id="showLine"><code>showLine(line) → lineHandle</code></dt>
      <dd>The inverse of <code>hideLine</code>—re-shows a previously
      hidden line, by number or by handle.</dd>

      <dt id="onDeleteLine"><code>onDeleteLine(line, func)</code></dt>
      <dd>Register a function that should be called when the line is
      deleted from the document.</dd>

      <dt id="lineInfo"><code>lineInfo(line) → object</code></dt>
      <dd>Returns the line number, text content, and marker status of
      the given line, which can be either a number or a handle
      returned by <code>setMarker</code>. The returned object has the
      structure <code>{line, handle, text, markerText, markerClass,
      lineClass, bgClass}</code>.</dd>

      <dt id="getLineHandle"><code>getLineHandle(num) → lineHandle</code></dt>
      <dd>Fetches the line handle for the given line number.</dd>

      <dt id="addWidget"><code>addWidget(pos, node, scrollIntoView)</code></dt>
      <dd>Puts <code>node</code>, which should be an absolutely
      positioned DOM node, into the editor, positioned right below the
      given <code>{line, ch}</code> position.
      When <code>scrollIntoView</code> is true, the editor will ensure
      that the entire node is visible (if possible). To remove the
      widget again, simply use DOM methods (move it somewhere else, or
      call <code>removeChild</code> on its parent).</dd>

      <dt id="matchBrackets"><code>matchBrackets()</code></dt>
      <dd>Force matching-bracket-highlighting to happen.</dd>

      <dt id="lineCount"><code>lineCount() → number</code></dt>
      <dd>Get the number of lines in the editor.</dd>

      <dt id="getCursor"><code>getCursor(start) → object</code></dt>
      <dd><code>start</code> is a boolean indicating whether the start
      or the end of the selection must be retrieved. If it is not
      given, the current cursor pos, i.e. the side of the selection
      that would move if you pressed an arrow key, is chosen.
      A <code>{line, ch}</code> object will be returned.</dd>
      <dt id="somethingSelected"><code>somethingSelected() → boolean</code></dt>
      <dd>Return true if any text is selected.</dd>
      <dt id="setCursor"><code>setCursor(pos)</code></dt>
      <dd>Set the cursor position. You can either pass a
      single <code>{line, ch}</code> object, or the line and the
      character as two separate parameters.</dd>
      <dt id="setSelection"><code>setSelection(start, end)</code></dt>
      <dd>Set the selection range. <code>start</code>
      and <code>end</code> should be <code>{line, ch}</code> objects.</dd>

      <dt id="getLine"><code>getLine(n) → string</code></dt>
      <dd>Get the content of line <code>n</code>.</dd>
      <dt id="setLine"><code>setLine(n, text)</code></dt>
      <dd>Set the content of line <code>n</code>.</dd>
      <dt id="removeLine"><code>removeLine(n)</code></dt>
      <dd>Remove the given line from the document.</dd>

      <dt id="getRange"><code>getRange(from, to) → string</code></td>
      <dd>Get the text between the given points in the editor, which
      should be <code>{line, ch}</code> objects.</dd>
      <dt id="replaceRange"><code>replaceRange(string, from, to)</code></dt>
      <dd>Replace the part of the document between <code>from</code>
      and <code>to</code> with the given string. <code>from</code>
      and <code>to</code> must be <code>{line, ch}</code>
      objects. <code>to</code> can be left off to simply insert the
      string at position <code>from</code>.</dd>

      <dt id="posFromIndex"><code>posFromIndex(index) → object</code></dt>
      <dd>Calculates and returns a <code>{line, ch}</code> object for a
      zero-based <code>index</code> who's value is relative to the start of the
      editor's text. If the <code>index</code> is out of range of the text then
      the returned object is clipped to start or end of the text
      respectively.</dd>
      <dt id="indexFromPos"><code>indexFromPos(object) → number</code></dt>
      <dd>The reverse of <a href="#posFromIndex"><code>posFromIndex</code></a>.</dd>
    </dl>

    <p>The following are more low-level methods:</p>

    <dl>
      <dt id="operation"><code>operation(func) → result</code></dt>
      <dd>CodeMirror internally buffers changes and only updates its
      DOM structure after it has finished performing some operation.
      If you need to perform a lot of operations on a CodeMirror
      instance, you can call this method with a function argument. It
      will call the function, buffering up all changes, and only doing
      the expensive update after the function returns. This can be a
      lot faster. The return value from this method will be the return
      value of your function.</dd>

      <dt id="refresh"><code>refresh()</code></dt>
      <dd>If your code does something to change the size of the editor
      element (window resizes are already listened for), or unhides
      it, you should probably follow up by calling this method to
      ensure CodeMirror is still looking as intended.</dd>

      <dt id="getInputField"><code>getInputField() → textarea</code></dt>
      <dd>Returns the hidden textarea used to read input.</dd>
      <dt id="getWrapperElement"><code>getWrapperElement() → node</code></dt>
      <dd>Returns the DOM node that represents the editor. Remove this
      from your tree to delete an editor instance.</dd>
      <dt id="getScrollerElement"><code>getScrollerElement() → node</code></dt>
      <dd>Returns the DOM node that is responsible for the sizing and
      the scrolling of the editor. You can change
      the <code>height</code> and <code>width</code> styles of this
      element to resize an editor. (You might have to call
      the <a href="#refresh"><code>refresh</code></a> method
      afterwards.)</dd>
      <dt id="getGutterElement"><code>getGutterElement() → node</code></dt>
      <dd>Fetches the DOM node that represents the editor gutter.</dd>

      <dt id="getStateAfter"><code>getStateAfter(line) → state</code></dt>
      <dd>Returns the mode's parser state, if any, at the end of the
      given line number. If no line number is given, the state at the
      end of the document is returned. This can be useful for storing
      parsing errors in the state, or getting other kinds of
      contextual information for a line.</dd>
    </dl>

    <p id="fromTextArea">Finally, the <code>CodeMirror</code> object
    itself has a method <code>fromTextArea</code>. This takes a
    textarea DOM node as first argument and an optional configuration
    object as second. It will replace the textarea with a CodeMirror
    instance, and wire up the form of that textarea (if any) to make
    sure the editor contents are put into the textarea when the form
    is submitted. A CodeMirror instance created this way has two
    additional methods:</p>

    <dl>
      <dt id="save"><code>save()</code></dt>
      <dd>Copy the content of the editor into the textarea.</dd>

      <dt id="toTextArea"><code>toTextArea()</code></dt>
      <dd>Remove the editor, and restore the original textarea (with
      the editor's current content).</dd>

      <dt id="getTextArea"><code>getTextArea() → textarea</code></dt>
      <dd>Returns the textarea that the instance was based on.</dd>
    </dl>

    <p id="defineExtension">If you want to define extra methods in terms
    of the CodeMirror API, it is possible to
    use <code>CodeMirror.defineExtension(name, value)</code>. This
    will cause the given value (usually a method) to be added to all
    CodeMirror instances created from then on.</p>

    <h2 id="addons">Add-ons</h2>

    <p>The <code>lib/util</code> directory in the distribution
    contains a number of reusable components that implement extra
    editor functionality. In brief, they are:</p>

    <dl>
      <dt id="util_dialog"><a href="../lib/util/dialog.js"><code>dialog.js</code></a></dt>
      <dd>Provides a very simple way to query users for text input.
      Adds an <code>openDialog</code> method to CodeMirror instances,
      which can be called with an HTML fragment that provides the
      prompt (should include an <code>input</code> tag), and a
      callback function that is called when text has been entered.
      Depends on <code>lib/util/dialog.css</code>.</dd>
      <dt id="util_searchcursor"><a href="../lib/util/searchcursor.js"><code>searchcursor.js</code></a></dt>
      <dd>Adds the <code>getSearchCursor(query, start, caseFold) →
      cursor</code> method to CodeMirror instances, which can be used
      to implement search/replace functionality. <code>query</code>
      can be a regular expression or a string (only strings will match
      across lines—if they contain newlines). <code>start</code>
      provides the starting position of the search. It can be
      a <code>{line, ch}</code> object, or can be left off to default
      to the start of the document. <code>caseFold</code> is only
      relevant when matching a string. It will cause the search to be
      case-insensitive. A search cursor has the following methods:
        <dl>
          <dt><code>findNext(), findPrevious() → boolean</code></dt>
          <dd>Search forward or backward from the current position.
          The return value indicates whether a match was found. If
          matching a regular expression, the return value will be the
          array returned by the <code>match</code> method, in case you
          want to extract matched groups.</dd>
          <dt><code>from(), to() → object</code></dt>
          <dd>These are only valid when the last call
          to <code>findNext</code> or <code>findPrevious</code> did
          not return false. They will return <code>{line, ch}</code>
          objects pointing at the start and end of the match.</dd>
          <dt><code>replace(text)</code></dt>
          <dd>Replaces the currently found match with the given text
          and adjusts the cursor position to reflect the
          replacement.</dd>
        </dl></dd>

      <dt id="util_search"><a href="../lib/util/search.js"><code>search.js</code></a></dt>
      <dd>Implements the search commands. CodeMirror has keys bound to
      these by default, but will not do anything with them unless an
      implementation is provided. Depends
      on <code>searchcursor.js</code>, and will make use
      of <a href="#util_dialog"><code>openDialog</code></a> when
      available to make prompting for search queries less ugly.</dd>
      <dt id="util_foldcode"><a href="../lib/util/foldcode.js"><code>foldcode.js</code></a></dt>
      <dd>Helps with code folding.
      See <a href="../demo/folding.html">the demo</a> for an example.
      Call <code>CodeMirror.newFoldFunction</code> with a range-finder
      helper function to create a function that will, when applied to
      a CodeMirror instance and a line number, attempt to fold or
      unfold the block starting at the given line. A range-finder is a
      language-specific function that also takes an instance and a
      line number, and returns an end line for the block, or null if
      no block is started on that line. This file
      provides <code>CodeMirror.braceRangeFinder</code>, which finds
      blocks in brace languages (JavaScript, C, Java,
      etc), <code>CodeMirror.indentRangeFinder</code>, for languages
      where indentation determines block structure (Python, Haskell),
      and <code>CodeMirror.tagRangeFinder</code>, for XML-style
      languages.</dd>
      <dt id="util_runmode"><a href="../lib/util/runmode.js"><code>runmode.js</code></a></dt>
      <dd>Can be used to run a CodeMirror mode over text without
      actually opening an editor instance.
      See <a href="../demo/runmode.html">the demo</a> for an
      example.</dd>
      <dt id="util_simple-hint"><a href="../lib/util/simple-hint.js"><code>simple-hint.js</code></a></dt>
      <dd>Provides a framework for showing autocompletion hints.
      Defines <code>CodeMirror.simpleHint</code>, which takes a
      CodeMirror instance and a hinting function, and pops up a widget
      that allows the user to select a completion. Hinting functions
      are function that take an editor instance, and return
      a <code>{list, from, to}</code> object, where <code>list</code>
      is an array of strings (the completions), and <code>from</code>
      and <code>to</code> give the start and end of the token that is
      being completed. Depends
      on <code>lib/util/simple-hint.css</code>.</dd>
      <dt id="util_javascript-hint"><a href="../lib/util/javascript-hint.js"><code>javascript-hint.js</code></a></dt>
      <dd>Defines <code>CodeMirror.javascriptHint</code>
      and <code>CodeMirror.coffeescriptHint</code>, which are simple
      hinting functions for the JavaScript and CoffeeScript
      modes.</dd>
      <dt id="util_match-highlighter"><a href="../lib/util/match-highlighter.js"><code>match-highlighter.js</code></a></dt>
      <dd>Adds a <code>matchHighlight</code> method to CodeMirror
      instances that can be called (typically from
      a <a href="#option_onCursorActivity"><code>onCursorActivity</code></a>
      handler) to highlight all instances of a currently selected word
      with the a classname given as a first argument to the method.
      Depends on
      the <a href="#util_searchcursor"><code>searchcursor</code></a>
      add-on. Demo <a href="../demo/matchhighlighter.html">here</a>.</dd>
      <dt id="util_closetag"><a href="../lib/util/closetag.js"><code>closetag.js</code></a></dt>
      <dd>Provides utility functions for adding automatic tag closing
      to XML modes. See
      the <a href="../demo/closetag.html">demo</a>.</dd>
    </dl>

    <h2 id="modeapi">Writing CodeMirror Modes</h2>

    <p>Modes typically consist of a single JavaScript file. This file
    defines, in the simplest case, a lexer (tokenizer) for your
    language—a function that takes a character stream as input,
    advances it past a token, and returns a style for that token. More
    advanced modes can also handle indentation for the language.</p>

    <p id="defineMode">The mode script should
    call <code>CodeMirror.defineMode</code> to register itself with
    CodeMirror. This function takes two arguments. The first should be
    the name of the mode, for which you should use a lowercase string,
    preferably one that is also the name of the files that define the
    mode (i.e. <code>"xml"</code> is defined <code>xml.js</code>). The
    second argument should be a function that, given a CodeMirror
    configuration object (the thing passed to
    the <code>CodeMirror</code> function) and an optional mode
    configuration object (as in
    the <a href="#option_mode"><code>mode</code></a> option), returns
    a mode object.</p>

    <p>Typically, you should use this second argument
    to <code>defineMode</code> as your module scope function (modes
    should not leak anything into the global scope!), i.e. write your
    whole mode inside this function.</p>

    <p>The main responsibility of a mode script is <em>parsing</em>
    the content of the editor. Depending on the language and the
    amount of functionality desired, this can be done in really easy
    or extremely complicated ways. Some parsers can be stateless,
    meaning that they look at one element (<em>token</em>) of the code
    at a time, with no memory of what came before. Most, however, will
    need to remember something. This is done by using a <em>state
    object</em>, which is an object that is always passed when
    reading a token, and which can be mutated by the tokenizer.</p>

    <p id="startState">Modes that use a state must define
    a <code>startState</code> method on their mode object. This is a
    function of no arguments that produces a state object to be used
    at the start of a document.</p>

    <p id="token">The most important part of a mode object is
    its <code>token(stream, state)</code> method. All modes must
    define this method. It should read one token from the stream it is
    given as an argument, optionally update its state, and return a
    style string, or <code>null</code> for tokens that do not have to
    be styled. For your styles, you can either use the 'standard' ones
    defined in the themes (without the <code>cm-</code> prefix), or
    define your own (as the <a href="../mode/diff/index.html">diff</a>
    mode does) and have people include a custom CSS file for your
    mode.<p>

    <p id="StringStream">The stream object encapsulates a line of code
    (tokens may never span lines) and our current position in that
    line. It has the following API:</p>

    <dl>
      <dt><code>eol() → boolean</code></dt>
      <dd>Returns true only if the stream is at the end of the
      line.</dd>
      <dt><code>sol() → boolean</code></dt>
      <dd>Returns true only if the stream is at the start of the
      line.</dd>

      <dt><code>peek() → character</code></dt>
      <dd>Returns the next character in the stream without advancing
      it. Will return <code>undefined</code> at the end of the
      line.</dd>
      <dt><code>next() → character</code></dt>
      <dd>Returns the next character in the stream and advances it.
      Also returns <code>undefined</code> when no more characters are
      available.</dd>

      <dt><code>eat(match) → character</code></dt>
      <dd><code>match</code> can be a character, a regular expression,
      or a function that takes a character and returns a boolean. If
      the next character in the stream 'matches' the given argument,
      it is consumed and returned. Otherwise, <code>undefined</code>
      is returned.</dd>
      <dt><code>eatWhile(match) → boolean</code></dt>
      <dd>Repeatedly calls <code>eat</code> with the given argument,
      until it fails. Returns true if any characters were eaten.</dd>
      <dt><code>eatSpace() → boolean</code></dt>
      <dd>Shortcut for <code>eatWhile</code> when matching
      white-space.</dd>
      <dt><code>skipToEnd()</code></dt>
      <dd>Moves the position to the end of the line.</dd>
      <dt><code>skipTo(ch) → boolean</code></dt>
      <dd>Skips to the next occurrence of the given character, if
      found on the current line (doesn't advance the stream if the
      character does not occur on the line). Returns true if the
      character was found.</dd>
      <dt><code>match(pattern, consume, caseFold) → boolean</code></dt>
      <dd>Act like a
      multi-character <code>eat</code>—if <code>consume</code> is true
      or not given—or a look-ahead that doesn't update the stream
      position—if it is false. <code>pattern</code> can be either a
      string or a regular expression starting with <code>^</code>.
      When it is a string, <code>caseFold</code> can be set to true to
      make the match case-insensitive. When successfully matching a
      regular expression, the returned value will be the array
      returned by <code>match</code>, in case you need to extract
      matched groups.</dd>

      <dt><code>backUp(n)</code></dt>
      <dd>Backs up the stream <code>n</code> characters. Backing it up
      further than the start of the current token will cause things to
      break, so be careful.</dd>
      <dt><code>column() → integer</code></dt>
      <dd>Returns the column (taking into account tabs) at which the
      current token starts. Can be used to find out whether a token
      starts a new line.</dd>
      <dt><code>indentation() → integer</code></dt>
      <dd>Tells you how far the current line has been indented, in
      spaces. Corrects for tab characters.</dd>

      <dt><code>current() → string</code></dt>
      <dd>Get the string between the start of the current token and
      the current stream position.</dd>
    </dl>

    <p id="blankLine">By default, blank lines are simply skipped when
    tokenizing a document. For languages that have significant blank
    lines, you can define a <code>blankLine(state)</code> method on
    your mode that will get called whenever a blank line is passed
    over, so that it can update the parser state.</p>

    <p id="copyState">Because state object are mutated, and CodeMirror
    needs to keep valid versions of a state around so that it can
    restart a parse at any line, copies must be made of state objects.
    The default algorithm used is that a new state object is created,
    which gets all the properties of the old object. Any properties
    which hold arrays get a copy of these arrays (since arrays tend to
    be used as mutable stacks). When this is not correct, for example
    because a mode mutates non-array properties of its state object, a
    mode object should define a <code>copyState</code> method,
    which is given a state and should return a safe copy of that
    state.</p>

    <p id="compareStates">By default, CodeMirror will stop re-parsing
    a document as soon as it encounters a few lines that were
    highlighted the same in the old parse as in the new one. It is
    possible to provide an explicit way to test whether a state is
    equivalent to another one, which CodeMirror will use (instead of
    the unchanged-lines heuristic) to decide when to stop
    highlighting. You do this by providing
    a <code>compareStates</code> method on your mode object, which
    takes two state arguments and returns a boolean indicating whether
    they are equivalent. See the XML mode, which uses this to provide
    reliable highlighting of bad closing tags, as an example.</p>

    <p id="indent">If you want your mode to provide smart indentation
    (though the <a href="#indentLine"><code>indentLine</code></a>
    method and the <code>indentAuto</code>
    and <code>newlineAndIndent</code> commands, which keys can be
    <a href="#option_extraKeys">bound</a> to), you must define
    an <code>indent(state, textAfter)</code> method on your mode
    object.</p>

    <p>The indentation method should inspect the given state object,
    and optionally the <code>textAfter</code> string, which contains
    the text on the line that is being indented, and return an
    integer, the amount of spaces to indent. It should usually take
    the <a href="#option_indentUnit"><code>indentUnit</code></a>
    option into account.</p>

    <p id="electricChars">Finally, a mode may define
    an <code>electricChars</code> property, which should hold a string
    containing all the characters that should trigger the behaviour
    described for
    the <a href="#option_electricChars"><code>electricChars</code></a>
    option.</p>

    <p>So, to summarize, a mode <em>must</em> provide
    a <code>token</code> method, and it <em>may</em>
    provide <code>startState</code>, <code>copyState</code>,
    <code>compareStates</code>, and <code>indent</code> methods. For
    an example of a trivial mode, see
    the <a href="../mode/diff/diff.js">diff mode</a>, for a more involved
    example, see the <a href="../mode/clike/clike.js">C-like
    mode</a>.</p>

    <p>Sometimes, it is useful for modes to <em>nest</em>—to have one
    mode delegate work to another mode. An example of this kind of
    mode is the <a href="../mode/htmlmixed/htmlmixed.js">mixed-mode HTML
    mode</a>. To implement such nesting, it is usually necessary to
    create mode objects and copy states yourself. To create a mode
    object, there are <code>CodeMirror.getMode(options,
    parserConfig)</code>, where the first argument is a configuration
    object as passed to the mode constructor function, and the second
    argument is a mode specification as in
    the <a href="#option_mode"><code>mode</code></a> option. To copy a
    state object, call <code>CodeMirror.copyState(mode, state)</code>,
    where <code>mode</code> is the mode that created the given
    state.</p>

    <p>To make indentation work properly in a nested parser, it is
    advisable to give the <code>startState</code> method of modes that
    are intended to be nested an optional argument that provides the
    base indentation for the block of code. The JavaScript and CSS
    parser do this, for example, to allow JavaScript and CSS code
    inside the mixed-mode HTML mode to be properly indented.</p>

    <p>Finally, it is possible to associate your mode, or a certain
    configuration of your mode, with
    a <a href="http://en.wikipedia.org/wiki/MIME">MIME</a> type. For
    example, the JavaScript mode associates itself
    with <code>text/javascript</code>, and its JSON variant
    with <code>application/json</code>. To do this,
    call <code>CodeMirror.defineMIME(mime, modeSpec)</code>,
    where <code>modeSpec</code> can be a string or object specifying a
    mode, as in the <a href="#option_mode"><code>mode</code></a>
    option.</p>

</div><div class="rightsmall blk">

    <h2>Contents</h2>

    <ul>
      <li><a href="#overview">Overview</a></li>
      <li><a href="#usage">Basic Usage</a></li>
      <li><a href="#config">Configuration</a></li>
      <li><a href="#keymaps">Keymaps</a></li>
      <li><a href="#styling">Customized Styling</a></li>
      <li><a href="#api">Programming API</a></li>
      <li><a href="#addons">Add-ons</a></li>
      <li><a href="#modeapi">Writing CodeMirror Modes</a></li>
    </ul>

</div></div>

<div style="height: 2em">&nbsp;</div>

  </body>
</html>