JS做加法精度问题

function addValue(value1,value2){
if(value1=="")value1="0";
if(value2=="")value2="0";
var temp1=0;
var temp2=0;
if(value1.indexOf(".")!=-1)
temp1=value1.length - value1.indexOf(".")-1;
if(value2.indexOf(".")!=-1)
temp2=value2.length - value2.indexOf(".")-1;

var temp=0;

if(temp1>temp2)
temp = (parseFloat(value1)+parseFloat(value2)).toFixed(temp1);
else
temp = (parseFloat(value1)+parseFloat(value2)).toFixed(temp2);

document.getElementById('test3').value= temp;

}