delegate-event-listener

[![Build Status][ci-img]][ci]
[![BrowserStack Status][browserstack-img]][browserstack]

Delegate event listener.

Features:

- Flexible usage with native addEventListener and removeEventListener
- Current target reference with event.delegateTarget property
- Prevents listener triggering if target element is inside form [disabled]
element
- Handles delegating of non-delegated events such as focus, blur,
mouseenter/leave, pointerenter/leave

Install

``sh
npm install delegate-event-listener --save
`

Usage

Given following markup and JS functionality clicking only on #frankie will
trigger event listener even though event handler is attached on #jackie.

`html


`js
import delegate from 'delegate-event-listener';

const element = document.querySelector('#jackie');

element.addEventListener(
'click',
delegate('#frankie', (e) => {
// e.delegateTarget === document.querySelector('#frankie')
// Clicked on #frankie!
})
);

// Delegating non-delegated events such as focus is achieved with alternative function output
element.addEventListener(
...delegate('focus', '#frankie', (e) => {
// e.delegateTarget === document.querySelector('#frankie')
// Clicked on #frankie!
})
);
`

API

$3

Returns: Function|array

Delegated function.

If delegate function call contains 3 arguments, first argument is event name
which will then be used to resolve proper delegated event. Array of values is
then returned, first argument being event name used to fix event (e.g.
mouseover for mouseenter), and second argument being event handler. Those
values should then be applied to addEventListener (either via spreading or
manual assignment).

Original event (one which was supplied to function) is available as
event.originalEventType. Resolved event is available to native event.type:

#### eventName

Type: string

Event name. Used only for alternative function output. Event will be mapped to
proper delegatable event (e.g. mouseenter for mouseover).

#### selector

Type: string

CSS selector whose ancestor is element on which event handler is attached. If
it’s empty string, event handler will be attached to element which called
addEventListener.

#### listener

Type: Function

Event listener for event handler.

Native Event object is decorated with event.delegateTarget property. This
property is same as node resolved from selector. event.currentTarget is equal
to node on which event listener is attached.

For non-delegated event handlers attached directly to an element,
event.delegateTarget will always be equal to event.currentTarget.

FAQ

$3

Event propagation in Event constructor is not active by default. You have to
explicitly enable it.

`js
document.body.addEventListener(
'click',
delegate('button', () => {
// …
})
);

// Setting bubbles: true makes event propagation active
document
.querySelector('button')
.dispatchEvent(new Event('click', { bubbles: true }));
`

Browser support

Tested in IE9+ and all modern browsers.

Test

For automated tests, run npm run test:automated (append :watch` for watcher
support).

License

MIT © Ivan Nikolić

[ci]: https://travis-ci.com/niksy/delegate-event-listener
[ci-img]: https://travis-ci.com/niksy/delegate-event-listener.svg?branch=master
[browserstack]: https://www.browserstack.com/
[browserstack-img]: https://www.browserstack.com/automate/badge.svg?badge_key=M1I1MHNIL2l2N1lSTVRNMjdEU09haDdKS2MvR0VNdjNLL3c5NGVydDJ0UT0tLUNCNTFvYWFwRjYzWkZjaEJsMEVXaGc9PQ==--61b9e0c915eac985bb6c4a299b2d37e55f33ff8e