base64encode

	function base64Encode(encodeStr){
		if(!encodeStr) return ;
		var BitPattern = '',result = '';
		var leastSignificantBits = ''
		var base64IndexTable = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
		for (var i = 0; i < encodeStr.length; i++) {
			var ASCIIChar = encodeStr.charCodeAt(i);
			var binaryStr = (ASCIIChar).toString(2),newBinaryStr='';
			for (var j = 0; j < 8-binaryStr.length; j++) {
				newBinaryStr += '0';
			}
			binaryStr = newBinaryStr+binaryStr;
			BitPattern += binaryStr;
		}
		if(BitPattern.length%24==0){
			for (var i = 0; i < BitPattern.length/6; i++) {
				var singleBase64CharIndex = parseInt(BitPattern.substring(6*i,6*(i+1)),2);
				result += base64IndexTable[singleBase64CharIndex];
			}
		}else{
		    var blockNumber = Math.floor((24-BitPattern.length%24)/6)
		    var buchong = (24-BitPattern.length%24)%6;
			for (var j = 0; j < buchong; j++) {
				BitPattern +='0';
			}
			for (var i = 0; i < BitPattern.length/6; i++) {
				var singleBase64CharIndex = parseInt(BitPattern.substring(6*i,6*(i+1)),2);
				result += base64IndexTable[singleBase64CharIndex];
			}
			for (var j = 0; j < blockNumber; j++) {
				result +='=';
			}
		}
		return result ;
	}