joelgriffith / object-observe-es5

An ES5 polyfill for the Object.observe method coming in ES6

ES5 Object.observe polyfill

After taking inspiration from eligrey, I've decided to implement an Object.observe polyfill that matches spec almost 100% (see below for differences). If you're not familiar with the API, HTML5 Rocks has a good writeup on it.

Testing

A full test-suite is included with this polyfill. You'll need mocha, and jshint installed globally for the best results. To run:

• npm install && npm test

Building

There is also a gulp file included to build yourself. This requires mocha, jshint, and gulp to be installed globally.

• gulp runs the default task, which is building, linting, and running the test suite.
• gulp test runs the mocha test suite.
• gulp build builds the minified js in build/observe.min.<build>.js
• gulp clean cleans the /build directory.
• gulp hint runs jshint on the /lib folder.

Differences

Though this polyfill has the majority of functionality that I anticipate people to use, there are a few differences.

Missing Features:

• Doesn't work with Arrays. This might be addressed in the future.
• Only supports the add, delete, and update events on an object. The Spec implements other low-level events, such as preventExtensions and frozen. These will be addressed at a later date.

API Differences

• Deleted properties don't have the oldValue parameter in the change payload.

Intended Uses

The most obvious use is for data-binding. When a user, or another 3rd party, makes changes to an object there can now be handlers in place for how to respond. This brings an incredible amount of automation and power to applications.

Support

This will work in any browser that has implemented ES5. To summarize: IE9+, Chrome 6+, FireFox 4+, Safari 5+, and Node.

License

The MIT License (MIT)

Copyright (c) 2014 Joel Griffith

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

object-observe-es5's Issues

This won't detect the addition of new properties or the deletion of existing properties

That's the problem with using getter/setters. The only polyfill that will really solve the problem is something that periodically compares objects to cached values to look for changes.

Make this work with Arrays