A split-screen Markdown editor and previewer
JavaScript CoffeeScript
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Crevasse is a simple Markdown editor with a live preview. It's written in CoffeeScript and available as a jQuery plugin.




  • Edit Markdown in one pane and see the preview update live in another
  • Built for custom interfaces and layouts. You specify the editor and the previewer elements, what you see on the demo page is just one implementation
  • Preview automatically scrolls to keep the user centered on what they are editing
  • Supports flexible dimensions as well as dynamically changing dimensions with JavaScript
  • Comes with default themes (shown on demo page) and supports custom themes
  • The raw Markdown is stored and edited in a simple textarea, making it easy to integrate with existing forms and backends
  • Supports Github Flavored Markdown and code highlighting
  • Supports converting tabs to a specified number of spaces in editor

Installation and Usage

  • Grab the latest code from the lib/ directory
  • Download all dependency libraries (see below or available in dependencies/)
  • Create a textarea for the editor and any element for the previewer.
<textarea id="your_editor"></textarea>
<div id="your_previewer"></div>
#your_editor, #your_previewer {
  width: 500px;
  height: 600px;
  display: inline-block;
  • Initialize Crevasse on the textarea and pass the previewer as an option
  previewer: $("#your_previewer")
  • Enjoy split-screen Markdown zen


Crevasse depends on a number of other libraries. They are listed below or you can find versions of each library guaranteed to work with Crevasse in the dependencies/ directory.

Advanced usage

Options (shown with defaults)

  previewer: null, // required. jQuery object or selector string
  editorStyle: "default", // theme to use for editor
  usePreviewerReset: true, // reset CSS for previewer pane
  previewerStyle: "github", // theme to use for previewer
  convertTabsToSpaces: 2 // number of spaces or false

Custom themes

Crevasse comes with default themes for the editor and previewer. If you'd like, you can customize the appearance of both.

Editor theme

Out of the box, the editor uses the default theme. This is controlled via the editorStyle option. If you'd like to use a custom theme, simply set editorStyle to a CSS class of your own.

Previewer theme

Out of the box, the previewer uses the github theme. The rendered Markdown will be styled the same as what you are used to seeing on GitHub. You can customize this via the previewerStyle option. If you'd like to use a custom theme, simply set previewerStyle to a CSS class of your own.

Code highlighter theme

The previewer uses "solarized-light" as its default code highlighting theme. However, you can load in any theme supported by Rianbow.js. See available themes

Support for flexible dimensions

If at any time the dimensions of the previewer or editor change, whether with JavaScript or a window resize, you will need to fire the crevasse.resize event on the corresponding element (your editor or previewer or both).

// Resize with window resize
$(window).resize(function () {

// Resize manually

Changing the value dynamically with JavaScript

If you would like to change the value of the textarea without user interaction, simply fire the change event on the textarea and Crevasse will update the preview.

$("#your_editor").val("Some new value").trigger("change");


  • Convert the textarea into a rich text editor and add Markdown syntax highlighting
  • Add some Markdown-specific editing improvements like adding a bullet automatically if you hit enter while already in a list.


  1. Fork and clone your fork
  2. Run $ cake build:development to automatically compile changes made in src/ to development/lib/
  3. Make changes to the library files in src/
  4. Test those changes in development/example.html
  5. Pull request!

If you'd like to build your own package for release, you can edit the version number in VERSION and run $ cake build to version and compile to lib/