Url Encoding and Decoding for Nested Objects.js

UrlEncoder = {

	/**
	* Encode a [deeply] nested object for use in a url
	* Assumes Array.each is defined
	*/
	encode: function(params, prefix) {
	
		var items = [];
		
		for(var field in params) {
			
			var key  = prefix ? prefix + "[" + field + "]" : field;
			var type = typeof params[field];
			
			switch(type) {
			
				case "object":
					
					//handle arrays appropriately x[]=1&x[]=3
					if(params[field].constructor == Array) {
						params[field].each(function(val) {
							items.push(key + "[]=" + val);
						}, this);
					} else {
						//recusrively construct the sub-object
						items = items.concat(this.encode(params[field], key));
					}
					break;
				case "function":
					break;
				default:
					items.push(key + "=" + escape(params[field]));
					break;
			}
		}

		return items.join("&");
	},
	
	/**
	* Decode a deeply nested Url
	*/
	decode: function(params) {
		
		var obj	  = {};
		var parts = params.split("&");
		
		parts.each(function(kvs) {

			var kvp = kvs.split("=");
			var key = kvp[0];
			var val = unescape(kvp[1]);
			
			if(/\[\w+\]/.test(key)) {

				var rgx = /\[(\w+)\]/g;
				var top = /^([^\[]+)/.exec(key)[0];
				var sub = rgx.exec(key);
				
				if(!obj[top]) {
					obj[top] = {};
				}
				
				var unroot = function(o) {
					
					if(sub == null) {
						return;
					}
					
					var sub_key = sub[1];
					
					sub = rgx.exec(key);
					
					if(!o[sub_key]) {
						o[sub_key] = sub ? {} : val;
					}
					
					unroot(o[sub_key]);
				};
				
				
				unroot(obj[top]);
				
			//array
			} else if(/\[\]$/.test(key)) {
				key = /(^\w+)/.exec(key)[0];
				if(!obj[key]) {
					obj[key] = [];
				}
				obj[key].push(val);
			} else {
				obj[key] = val;
			}
			
		});
		
		return obj;
	}
	
};