Ember-cli-dom-observer NPM

ember-cli-dom-observer

Implementation of MutationObserver / DOM Mutation Observers as an Ember component.

Detailed Documentation

Uses

Browser extensions - You've created a browser extension in Ember and need to monitor changes to the DOM to trigger your extension.
Overcome HTML shortcomings by allowing you to monitor changes to attributes, elements and nodes (anything in the DOM).
Hook into 3rd party components that you are otherwise unable to see changes that these components make to the DOM (e.g. Jquery Addon).
Troubleshooting - Examine misbehaving components as they change within the DOM.

Features

Fast DOM change event capture.
Capture snapshot DOM change comparison events for specific elements.
Any DOM change can be captured including very complex events.
Finite control allowing you to select what elements are observed and what changes to monitor.

How does this work?

By using the Ember component methodology to wrap a MutationObserver around an HTML element (see example code below).

Further information on MutationObserver can be found in these excellent blog posts:

Addon Installation

ember install ember-cli-dom-observer

Requirements

Ember 2.15
- Older Ember 2.x versions may work but this component has not been used/tested with previous versions.
- If you are using Ember 1.x or your version of Ember does not work with this component then use this Addon instead.
Only works with modern web browsers
- Chrome 49+
- Edge 14+
- Firefox 52+
- IE 11
- Opera 46+
- Safari 10.1+

Addon Usage

{{#mutation-observer
    handleMutations=(action "handleMutations")
    attributes=true
    childList=true
    characterData=true
    subtree=true
    attributeFilter='["JSON","string","array"]'
}}
  <ol contenteditable>
    <li>Click here and press enter</li>
  </ol>
{{/mutation-observer}}

  import Ember from 'ember';
  export default Ember.Component.extend({

  actions: 
  {
    /**
     * MutationObserver triggered events action handler
     * 
     * @param {MutationRecord[]} mutationRecords The triggered mutation records
     * @param {MutationObserver} observer
     */
    handleMutations(mutationRecords, observer) {
      // Do something with mutation records
    }
  }
})

In the example above MutationRecords will be sent to the handleMutations() action function when any changes (e.g. new <LI> node was added) to the ordered list occur.

This Addon can also be used as a standalone component by using the targetId property to indicate the element to be observed as in the example below.

{{mutation-observer
handleMutations=(action "handleMutations")
attributes=false
childList=false
characterData=true
subtree=true
targetId="btn"}}

<button id="btn" contenteditable="true">Click Here to Change Button Text</button>
<p>Button Text: {{buttonText}}</p>

  import Ember from 'ember';
  export default Ember.Component.extend(
{
  buttonText: null,

  actions: 
  {
    handleMutations(mutations, observer) {
      let self=this;
      mutations.forEach(function (mutation) 
      {
        if (mutation.type === 'characterData') {
          self.set('buttonText', mutation.target.textContent);
          observer.takeRecords(); // Empty the mutation queue.
        }
      });
    }
  }
})

IMPORTANT NOTE: It is possible to have more than one observed element (multiple mutation-observer components) on a page and have each observed element use the same mutationHandler action.

However this is not best practice, and can cause recursion issues.

Each element you wrap in a component or set as the targetId should have an individual mutationHandler action. See the code in tests/dummy/app/components/example-mutation.js for an examples of best practice and bad practice.