eslint-plugin-delegated-events

Disallow delegating high-frequency events.

The delegated-events library registers all event listeners on document, using selectors to determine an observer's interest in each event.

on('click', '.js-button', function(event) {
  console.log('clicked', this)
})

This is appropriate for most events, like click and change, but events fired at a high rate need to be directly bound with element.addEventListener to avoid performance problems.

This lint rule disallows delegated event listeners on the following events:

• input
• keydown
• keypress
• keyup
• mouseout
• mouseover
• mousemove
• scroll

Top level listener registration

Registering a delegated event listener by calling on in a conditional branch, loop, or function can result in duplicate registrations and invoking the listener multiple times. The global-on lint rule requires on to be called only in the top level module scope.

Installation

You'll first need to install ESLint:

$ npm install eslint --save-dev

Next, install eslint-plugin-delegated-events:

$ npm install eslint-plugin-delegated-events --save-dev

Note: If you installed ESLint globally (using the -g flag) then you must also install eslint-plugin-delegated-events globally.

Usage

Add delegated-events to the plugins section of your .eslintrc configuration file. You can omit the eslint-plugin- prefix:

{
  "plugins": [
    "delegated-events"
  ],
  "rules": {
    "delegated-events/global-on": 2,
    "delegated-events/no-high-freq": 2
  }
}

Development

npm install
npm test

License

Distributed under the MIT license. See LICENSE for details.