"^([^=]+)"
[code=JScript]base64 = "MTE3LjE2MDI0MTYsMzkuMTY2MzIwNDU=";
re = new RegExp("^([^=]+)","g");
base64 = re.exec(base64)[0];
alert(base64);[code]
[code=JScript]base64 = "MTE3LjE2MDI0MTYsMzkuMTY2MzIwNDU=";
re = new RegExp("^([^=]+)","g");
base64 = re.exec(base64)[0];
alert(base64);[code]
var str = "MTE3LjE2MDI0MTYsMzkuMTY2MzIwNDU=";
alert(str.substring(0,str.length - 1));
</script>
alert(str.substring(0,str.lastIndexOf('=')));
"^\S+\s=\s(\S+)=$"
{//取得两个"="号之间的字符串
var re = new RegExp("=([^=]+)=","ig");
var Arr = re.exec(Str);
return RegExp.$1;
}//测试
alert(GetMyStr("base64 = MTE3LjE2MDI0MTYsMzkuMTY2MzIwNDU= "));