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<title>CodeMirror: User Manual</title>
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<h1><span class="logo-braces">{ }</span> <a href="">CodeMirror</a></h1>
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<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,
the <a href="">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
<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
<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"
<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
<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>
<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="">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
<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
<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
<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="">tab
index</a> to assign to the editor. If not given, no tab index
will be assigned.</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>
<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
<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
<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>
<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
<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>,
<dd>These are used to style matched (or unmatched) brackets.</dd>
<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>
<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
<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
<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
<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) → object</code></dt>
<dd>Returns an <code>{x, y, yBot}</code> object containing the
coordinates of the cursor 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) → 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
<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:
<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>
<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
<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
<dt id="indexFromPos"><code>indexFromPos(object) → number</code></dt>
<dd>The reverse of <a href="#posFromIndex"><code>posFromIndex</code></a>.</dd>
<p>The following are more low-level methods:</p>
<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
<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>
<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>
<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>
<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>
<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:
<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>
<dd>Replaces the currently found match with the given text
and adjusts the cursor position to reflect the
<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
<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
<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
<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>
<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
<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>
<dt><code>eol() → boolean</code></dt>
<dd>Returns true only if the stream is at the end of the
<dt><code>sol() → boolean</code></dt>
<dd>Returns true only if the stream is at the start of the
<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
<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
<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
<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>
<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>
<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
<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
<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>
<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
<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
<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="">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>
</div><div class="rightsmall blk">
<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>
<div style="height: 2em">&nbsp;</div>