eventslibjs

Events

A tiny (700 byte minified and gzipped) event delegation helper library.

Events lets you setup individual event listeners throughout your code, but runs them all in a single event listener behind-the-scenes. Learn more about why you should use event delegation.

View the Demo on CodePen →

Installation | API | Selectors | Browser Compatibility | License

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Installation

Compiled and production-ready code can be found in the dist directory. The src directory contains development code.

There are two versions of Events: the standalone version, and one that comes preloaded with a polyfill for closest(), which is only supported in newer browsers.

If you're including your own polyfills or don't want to enable this feature for older browsers, use the standalone version. Otherwise, use the version with polyfills.

Direct Download

You can download the files directly from GitHub.

<script src="path/to/events.polyfills.min.js"></script>

CDN

You can also use the jsDelivr CDN. I recommend linking to a specific version number or version range to prevent major updates from breaking your site. Smooth Scroll uses semantic versioning.

<!-- Always get the latest version -->
<!-- Not recommended for production sites! -->
<script src="https://cdn.jsdelivr.net/gh/cferdinandi/events/dist/events.polyfills.min.js"></script>
 
<!-- Get minor updates and patch fixes within a major version -->
<script src="https://cdn.jsdelivr.net/gh/cferdinandi/events@1/dist/events.polyfills.min.js"></script>
 
<!-- Get patch fixes within a minor version -->
<script src="https://cdn.jsdelivr.net/gh/cferdinandi/events@1.0/dist/events.polyfills.min.js"></script>
 
<!-- Get a specific version -->
<script src="https://cdn.jsdelivr.net/gh/cferdinandi/events@1.0.0/dist/events.polyfills.min.js"></script>

NPM

You can also use NPM (or your favorite package manager).

npm install eventslibjs

API

on()

Add an event listener.

/**
 * Add an event
 * @param  {String}   types    The event type or types (space separated)
 * @param  {String}   selector The selector to run the event on
 * @param  {Function} callback The function to run when the event fires
 */
events.on(types, selector, callback);

Example

events.on('click', '.sandwich', function (event) {
    var filling = event.target.getAttribute('data-sandwich-filling');
    console.log(filling);
});

You can attach the same callback to multiple event types or selectors by separating them with a comma.

// Attach to multiple events
events.on('click, input', '.sandwich', myCallback);
 
// Attach to multiple selectors
events.on('click', '.sandwich, .tuna, .turkey', myCallback);

off()

Remove an event listener. All three arguments must be identical to the ones used when setting up the listener.

/**
 * Remove an event
 * @param  {String}   types    The event type or types (space separated)
 * @param  {String}   selector The selector to remove the event from
 * @param  {Function} callback The function to remove
 */
events.off(types, selector, callback);

Example

events.off('click', '.sandwich', function (event) {
    var filling = event.target.getAttribute('data-sandwich-filling');
    console.log(filling);
});

You can also remove all events of a particular type by passing in just the event type.

// Remove all click events
events.off('click');

once()

Run an event callback exactly once and then automatically remove it. Works the same as the on() method.

/**
 * Add an event, and automatically remove it after it's first run
 * @param  {String}   types    The event type or types (space separated)
 * @param  {String}   selector The selector to run the event on
 * @param  {Function} callback The function to run when the event fires
 */
events.once(types, selector, callback);

Example

events.once('click', '.tuna', function (event) {
    console.log('Tuna sandwich!');
});

get()

Get an immutable list of all active event listeners.

Returns an object. Each active event type is a key, with an array of selector/callback objects as its property.

var activeEvents = events.get();

Selectors

You can pass in any valid CSS selector (or combination of selectors). Events uses closest() under-the-hood to check if the element that triggered the event matches the selector (or is inside an element that does).

// ID as a selector
events.on('click', '#turkey', myCallback);
 
// Data attribute selector
events.on('click', '[data-sandwich="turkey"]', myCallback);
 
// Multiple selectors
events.on('click', '.turkey, .tuna, .ham', myCallback);

To run your callback on any element, pass in * for a selector.

events.on('click', '*', myCallback);

You can also pass in a node instead of a selector string.

var sandwich = document.querySelector('.sandwich');
events.on('click', sandwich, myCallback);

Browser Compatibility

Events works in all modern browsers, and IE 9 and above.

Polyfills

Support back to IE9 requires a polyfill for the closest() method. Use the included polyfills version of Events, or include your own.

License

The code is available under the MIT License.