保留2位小数
function ja(){var a=0.00;
for(var i=0;i
document.getElementsByName("a3[]")[i].value=(document.getElementsByName("a2[]")[i].valuedocument.getElementsByName("a1[]")[i].value).toFixed(2) ;
a=parseFloat(a) + parseFloat(document.getElementsByName("a3[]")[i].value);}
document.getElementsByName("a3")[0].value=a.toFixed(2);