jQuery — New Wave JavaScript

Contribution Guides

In the spirit of open source software development, jQuery always encourages community code contribution. To help you get started and before you jump into writing code, be sure to read these important contribution guidelines thoroughly:

1. Getting Involved
2. Core Style Guide
3. Writing Code for jQuery Foundation Projects

Environments in which to use jQuery

• Browser support differs between the master branch and the compat branch. Specifically, the master branch does not support legacy browsers such as IE8. The jQuery team continues to provide support for legacy browsers on the compat branch. Use the latest compat release if support for those browsers is required. See browser support for more info.
• To use jQuery in Node, browser extensions, and other non-browser environments, use only master branch releases given the name "jquery" rather than "jquery-compat". The compat branch does not support these environments.

What you need to build your own jQuery

In order to build jQuery, you need to have the latest Node.js/npm and git 1.7 or later. Earlier versions might work, but are not supported.

For Windows, you have to download and install git and Node.js.

OS X users should install Homebrew. Once Homebrew is installed, run brew install git to install git, and brew install node to install Node.js.

Linux/BSD users should use their appropriate package managers to install git and Node.js, or build from source if you swing that way. Easy-peasy.

How to build your own jQuery

Clone a copy of the main jQuery git repo by running:

git clone git://github.com/jquery/jquery.git

Enter the jquery directory and run the build script:

cd jquery && npm run build

The built version of jQuery will be put in the dist/ subdirectory, along with the minified copy and associated map file.

If you want to create custom build or help with jQuery development, it would be better to install grunt command line interface as a global package:

npm install -g grunt-cli

Make sure you have grunt installed by testing:

grunt -V

Now by running the grunt command, in the jquery directory, you can build a full version of jQuery, just like with an npm run build command:

grunt

There are many other tasks available for jQuery Core:

grunt -help

Modules

Special builds can be created that exclude subsets of jQuery functionality. This allows for smaller custom builds when the builder is certain that those parts of jQuery are not being used. For example, an app that only used JSONP for $.ajax() and did not need to calculate offsets or positions of elements could exclude the offset and ajax/xhr modules.

Any module may be excluded except for core, and selector. To exclude a module, pass its path relative to the src folder (without the .js extension).

Some example modules that can be excluded are:

• ajax: All AJAX functionality: $.ajax(), $.get(), $.post(), $.ajaxSetup(), .load(), transports, and ajax event shorthands such as .ajaxStart().
• ajax/xhr: The XMLHTTPRequest AJAX transport only.
• ajax/script: The <script> AJAX transport only; used to retrieve scripts.
• ajax/jsonp: The JSONP AJAX transport only; depends on the ajax/script transport.
• css: The .css() method plus non-animated .show(), .hide() and .toggle(). Also removes all modules depending on css (including effects, dimensions, and offset).
• deprecated: Methods documented as deprecated but not yet removed.
• dimensions: The .width() and .height() methods, including inner- and outer- variations.
• effects: The .animate() method and its shorthands such as .slideUp() or .hide("slow").
• event: The .on() and .off() methods and all event functionality. Also removes event/alias.
• event/alias: All event attaching/triggering shorthands like .click() or .mouseover().
• offset: The .offset(), .position(), .offsetParent(), .scrollLeft(), and .scrollTop() methods.
• wrap: The .wrap(), .wrapAll(), .wrapInner(), and .unwrap() methods.
• core/ready: Exclude the ready module if you place your scripts at the end of the body. Any ready callbacks bound with jQuery() will simply be called immediately. However, jQuery(document).ready() will not be a function and .on("ready", ...) or similar will not be triggered.
• deferred: Exclude jQuery.Deferred. This also removes jQuery.Callbacks. Note that modules that depend on jQuery.Deferred(AJAX, effects, core/ready) will not be removed and will still expect jQuery.Deferred to be there. Include your own jQuery.Deferred implementation or exclude those modules as well (grunt custom:-deferred,-ajax,-effects,-core/ready).
• exports/global: Exclude the attachment of global jQuery variables ($ and jQuery) to the window.
• exports/amd: Exclude the AMD definition.

As a special case, you may also replace Sizzle by using a special flag grunt custom:-sizzle.

• sizzle: The Sizzle selector engine. When this module is excluded, it is replaced by a rudimentary selector engine based on the browser's querySelectorAll method that does not support jQuery selector extensions or enhanced semantics. See the selector-native.js file for details.

Note: Excluding Sizzle will also exclude all jQuery selector extensions (such as effects/animatedSelector and css/hiddenVisibleSelectors).

Note: Removing Sizzle is not supported on the compat branch.

The build process shows a message for each dependent module it excludes or includes.

AMD name

As an option, you can set the module name for jQuery's AMD definition. By default, it is set to "jquery", which plays nicely with plugins and third-party libraries, but there may be cases where you'd like to change this. Simply set the "amd" option:

grunt custom --amd="custom-name"

Or, to define anonymously, set the name to an empty string.

grunt custom --amd=""

Custom Build Examples

To create a custom build, first check out the version:

git pull; git checkout VERSION

Where VERSION is the version you want to customize. Then, make sure all Node dependencies are installed:

npm install

Create the custom build using the grunt custom option, listing the modules to be excluded.

Exclude all ajax functionality:

grunt custom:-ajax

Excluding css removes modules depending on CSS: effects, offset, dimensions.

grunt custom:-css

Exclude a bunch of modules:

grunt custom:-ajax,-css,-deprecated,-dimensions,-effects,-event/alias,-offset,-wrap

For questions or requests regarding custom builds, please start a thread on the Developing jQuery Core section of the forum. Due to the combinatorics and custom nature of these builds, they are not regularly tested in jQuery's unit test process. The non-Sizzle selector engine currently does not pass unit tests because it is missing too much essential functionality.

Running the Unit Tests

Make sure you have the necessary dependencies:

npm install

Start grunt watch or npm start to auto-build jQuery as you work:

grunt watch

Run the unit tests with a local server that supports PHP. Ensure that you run the site from the root directory, not the "test" directory. No database is required. Pre-configured php local servers are available for Windows and Mac. Here are some options:

• Windows: WAMP download
• Mac: MAMP download
• Linux: Setting up LAMP
• Mongoose (most platforms)

Building to a different directory

To copy the built jQuery files from /dist to another directory:

grunt && grunt dist:/path/to/special/location/

With this example, the output files would be:

/path/to/special/location/jquery.js
/path/to/special/location/jquery.min.js

To add a permanent copy destination, create a file in dist/ called ".destination.json". Inside the file, paste and customize the following:

{
  "/Absolute/path/to/other/destination": true
}

Additionally, both methods can be combined.

Essential Git

As the source code is handled by the Git version control system, it's useful to know some features used.

Cleaning

If you want to purge your working directory back to the status of upstream, the following commands can be used (remember everything you've worked on is gone after these):

git reset --hard upstream/master
git clean -fdx

Rebasing

For feature/topic branches, you should always use the --rebase flag to git pull, or if you are usually handling many temporary "to be in a github pull request" branches, run the following to automate this:

git config branch.autosetuprebase local

(see man git-config for more information)

Handling merge conflicts

If you're getting merge conflicts when merging, instead of editing the conflicted files manually, you can use the feature git mergetool. Even though the default tool xxdiff looks awful/old, it's rather useful.

The following are some commands that can be used there:

• Ctrl + Alt + M - automerge as much as possible
• b - jump to next merge conflict
• s - change the order of the conflicted lines
• u - undo a merge
• left mouse button - mark a block to be the winner
• middle mouse button - mark a line to be the winner
• Ctrl + S - save
• Ctrl + Q - quit

QUnit Reference

Test methods

expect( numAssertions );
stop();
start();

Note: QUnit's eventual addition of an argument to stop/start is ignored in this test suite so that start and stop can be passed as callbacks without worrying about their parameters.

Test assertions

ok( value, [message] );
equal( actual, expected, [message] );
notEqual( actual, expected, [message] );
deepEqual( actual, expected, [message] );
notDeepEqual( actual, expected, [message] );
strictEqual( actual, expected, [message] );
notStrictEqual( actual, expected, [message] );
throws( block, [expected], [message] );

Test Suite Convenience Methods Reference (See test/data/testinit.js)

Returns an array of elements with the given IDs

q( ... );

Example:

q("main", "foo", "bar");

=> [ div#main, span#foo, input#bar ]

Asserts that a selection matches the given IDs

t( testName, selector, [ "array", "of", "ids" ] );

Example:

t("Check for something", "//[a]", ["foo", "baar"]);

Fires a native DOM event without going through jQuery

fireNative( node, eventType )

Example:

fireNative( jQuery("#elem")[0], "click" );

Add random number to url to stop caching

url( "some/url.php" );

Example:

url("data/test.html");

=> "data/test.html?10538358428943"


url("data/test.php?foo=bar");

=> "data/test.php?foo=bar&10538358345554"

Load tests in an iframe

Loads a given page constructing a url with fileName: "./data/" + fileName + ".html" and fires the given callback on jQuery ready (using the jQuery loading from that page) and passes the iFrame's jQuery to the callback.

testIframe( fileName, testName, callback );

Callback arguments:

callback( jQueryFromIFrame, iFrameWindow, iFrameDocument );

Load tests in an iframe (window.iframeCallback)

Loads a given page constructing a url with fileName: "./data/" + fileName + ".html" The given callback is fired when window.iframeCallback is called by the page. The arguments passed to the callback are the same as the arguments passed to window.iframeCallback, whatever that may be.

testIframeWithCallback( testName, fileName, callback );

Questions?

If you have any questions, please feel free to ask on the Developing jQuery Core forum or in #jquery on irc.freenode.net.