angularjs decorator to support ie8 catch

When using the angularjs $q library with ES3 browsers (IE8 etc) you get an ‘Expected identifier’ error when you try and use the catch method on angularjs $q library. This is because catch is a reserved word in ES3 and reserved words are not supported as property names in ES3. To get round the problem you can access the function using square bracket notation. Personally I find this kind of syntax rather ugly.

	doSomething()
	.then(doSomethingElse)
	["catch"](allTheThings);

The first thing I wanted to do was provide a nicer syntax. The following artice has a good explanation of how to create a decorator for the $q service so that you can add your own methods onto it. The problem with the $q service is that you need to decorate the thing that gets passed back from the functions ‘defer’, ‘when’ ‘reject’ and ‘all’. Rather than just putting it on $q.

This means that we can now call

	doSomething()
	.then(doSomethingElse)
	.error(allTheThings);

and IE8 wont complain about it. Wonderful. The other thing I wanted to do was to make sure that everyone uses error instead of catch. So to guide people into this I’ve re-implemented catch to throw an exception.