Emit

Emit events on DOM element interaction using data-emit attributes.

Install

npm install --save emit-bindings

To include a prebuilt version directly in your page, use build/(version)/emit-bindings.js or build/(version)/emit-bindings.min.js:

<script type="text/javascript" src="build/(version)/emit-bindings.min.js"></script>

<script>
const Emit = require( 'emit-bindings' );

const emit = Object.assign( {}, Emit );

emit.monitor( document );

emit.on( 'foo', function( event ) {
    console.log( 'got a foo event' );
} );
</script>

Examples

Check out the examples/index.html

Why would I need this?

Emit is a simple, small (~12kb minified, ~5kb minified+gzipped) way to bind javascript actions to DOM nodes without using the more classic selector style favored by jQuery. It allows for better separation of concerns: no longer are element classes how you find and bind to actions in your UI. Instead, you mark up your DOM with the events you'd like various elements to emit when they are clicked (or touched, Emit also helps eliminate the 300ms click delay on mobile devices).

It is similar to Google's JsAction, except it is simpler and smaller (but, of course, less robust).

Advanced Usage

Options

debounce

Will debounce this event, only firing 250ms after the user has stopped interacting with the element. This is great for text input fields where you don't want to fire after each keystroke, but once the user has paused in their typing.

<input type="text" data-emit="changed" data-emit-options="debounce" />

allowdefault

Allows the default action. By default, emit will prevent the default action. By adding this option, the default will happen as well. This can be useful for navigation links where you want the browser to navigate, but you also want to be able to listen for an event.

<a href="/foo" data-emit='foo' data-emit-options="allowdefault">Emit 'foo', also navigate to /foo</a>

It's also usually necessary on something like a checkbox, where you want the box to be checked when the user clicks it.

<input type="checkbox" data-emit="checked" data-emit-options="allowdefault">Emit 'checked' but also check the checkbox.</input>

allowpropagate

Allows propagation. By default, emit will stop the propagation of an event. Setting this option will allow the event to continue propagating.

<button data-emit="clicked" data-emit-options="allowpropagate">Emit 'clicked' but don't stop event propagation.</button>

Ignoring events

Sometimes you don't want to listen to all the normal events (click, touchend, input, submit):

<a data-emit="foo" data-emit-ignore="click">foo</a> <!- will not emit 'foo' when clicked -->

Validators

You can add/remove 'validators' within Emit that can validate that a given event should fire.

If one of the validators fails on an element, the event will be stopped and eaten at that element.

Emit.add_validator

add_validator will add a validation function to Emit. It takes a single function as an argument.

The validation function will be called back when Emit is handling an event. The function's this context will be set to Emit and it will received two arguments: the element being processed and the event:

// add a validator to stop clicks on elements that have the data-busy attribute

emit.add_validator( function( element, event ) {
    return !element.dataset.busy;
} );

Emit.remove_validator

remove_validator will remove the given validation function from Emit's list of validators. It takes a single argument: the function to remove.

function check_busy( element, event ) {
    return !element.dataset.busy;
}

emit.add_validator( check_busy );

emit.remove_validator( check_busy );

License

MIT

Changelog

4.0.0

• ignore "similar" events (eg: click immediately followed by input on a checkbox)
• bumped major version in case this causes compatibility issues

3.0.5

• fix clicks being ignored

3.0.4

• fix late-firing click events

3.0.3

• code cleanup and minor improvement to event handling

3.0.2

• handle empty lists

3.0.1

• fix internal string => hash

3.0.0

• update to es2015 const/let
• remove singleton
• update API and variable naming conventions
• move away from function/prototype and toward Object.assign() inheritance
• remove dependency on EventEmitter

2.0.0

• event.emitTarget -> event.el

1.2.x

• Refactored dependencies and build process

1.1.1

• Handle hitting basic types (a, input, button) even when they have an element inside them.

1.1.0

• Handle event propagation differently to better allow for multiple instances of emit.

1.0.0

• Switch to browserify.

0.0.11

• Allow inputs on A tags through unless the A tag has a data-emit attribute

0.0.10

• Add a 'debounce' option

0.0.9

• Fix scrolling triggering events
• jshint/beautify

0.0.8

• Allow for emitting multiple comma-separated events

0.0.7

• Add ability to add/remove validators

0.0.6

• Allow clicks on file inputs
• Fix an issue with isPropagationStopped
• Fix an issue with preventing defaults on bubbled events
• Fix an issue with checkbox/radio and prevent default

0.0.5

• Add event.emitTarget instead of possibly read-only currentTarget

0.0.4

• Add select element handling

0.0.3

• Add data-emit-ignore support
• Fix submit/input handling to only emit on appropriate events

0.0.2

• Make sure events have a currentTarget that points to the current element

0.0.1

• Initial release