js实现urlencode和urldecode

最近发现写往cookie里面写值读出来是经过URLEncode过的。所以需要用js解码.所以用js实现了urlencode和urldecode

var littleUrl ={
		// public method for url encoding
		encode : function (string){
			return escape(this._utf8_encode(string));
		}
		,
		// public method for url decoding
		decode : function (string){
			return this._utf8_decode(unescape(string));
		}
		,
		// private method for UTF-8 encoding
		_utf8_encode : function (string){
			string = string.replace(/\r\n/g,"\n");
			var utftext = "";
			for (var n = 0; n < string.length; n++){
				var c = string.charCodeAt(n);
				if (c < 128){
					utftext += String.fromCharCode(c);
				}
				else
				if((c > 127) && (c < 2048)){
					utftext += String.fromCharCode((c >> 6) | 192);
					utftext += String.fromCharCode((c & 63) | 128);
				}
				else{
					utftext += String.fromCharCode((c >> 12) | 224);
					utftext += String.fromCharCode(((c >> 6) & 63) | 128);
					utftext += String.fromCharCode((c & 63) | 128);
				}
			}
			return utftext;
		}
		,
		// private method for UTF-8 decoding
		_utf8_decode : function (utftext){
			var string = "";
			var i = 0;
			var c = c1 = c2 = 0;
			while ( i < utftext.length ){
				c = utftext.charCodeAt(i);
				if (c < 128){
					string += String.fromCharCode(c);
					i++;
				}
				else
				if((c > 191) && (c < 224)){
					c2 = utftext.charCodeAt(i+1);
					string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
					i += 2;
				}
				else{
					c2 = utftext.charCodeAt(i+1);
					c3 = utftext.charCodeAt(i+2);
					string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
					i += 3;
				}
			}
			return string;
		}
	}