js判断字符长度

function getByteLen(){

var val=document.getElementById("txtPrizeNote").value;

var re = new RegExp("[\\u4e00-\\u9fa5]","");// 中文

var len = 0;

for(var i=val.length;i>0;i--){

var singleVal = val.substring(i,i-1);// 单个

if(re.test(singleVal))

len+=2;

else

len++;

var tempVal = val.substring(0,i-1);// 剩余

//alert(tempVal+" = = "+singleVal);

}

alert(len);

}