array.observe.polyfill.js

Object.observe && !Array.observe && (function(O, A) {
	"use strict";
	
	var notifier = O.getNotifier,
		perform = "performChange",
		original = "_original",
		type = "splice";
	
	var wrappers = {
		push: function push(item) {
			var args = arguments,
				ret = push[original].apply(this, args);
	
			notifier(this)[perform](type, function() {
				return {
					index: ret - args.length,
					addedCount: args.length,
					removed: []
				};
			});
	
			return ret;
		},
		unshift: function unshift(item) {
			var args = arguments,
				ret = unshift[original].apply(this, args);
	
			notifier(this)[perform](type, function() {
				return {
					index: 0,
					addedCount: args.length,
					removed: []
				};
			});
	
			return ret;
		},
		pop: function pop() {
			var len = this.length,
				item = pop[original].call(this);
	
			if (this.length !== len)
				notifier(this)[perform](type, function() {
					return {
						index: this.length,
						addedCount: 0,
						removed: [ item ]
					};
				}, this);
	
			return item;
		},
		shift: function shift() {
			var len = this.length,
				item = shift[original].call(this);
	
			if (this.length !== len)
				notifier(this)[perform](type, function() {
					return {
						index: 0,
						addedCount: 0,
						removed: [ item ]
					};
				}, this);
	
			return item;
		},
		splice: function splice(start, deleteCount) {
			var args = arguments,
				removed = splice[original].apply(this, args);
	
			if (removed.length || args.length > 2)
				notifier(this)[perform](type, function() {
					return {
						index: start,
						addedCount: args.length - 2,
						removed: removed
					};
				}, this);
	
			return removed;
		}
	};
	
	for (var wrapper in wrappers) {
		wrappers[wrapper][original] = A.prototype[wrapper];
		A.prototype[wrapper] = wrappers[wrapper];
	}
	
	A.observe = function(object, handler) {
		return O.observe(object, handler, [ "add", "update", "delete", type ]);
	};
	A.unobserve = O.unobserve;
	
	})(Object, Array);