乘法运算保留两位小数

var num=accMul(0.123,2.21);//0.27183
num=decimal(num,2);//0.27

//精确乘法运算
function accMul(arg1,arg2){
  var m=0,s1=arg1.toString(),s2=arg2.toString();
  try{m+=s1.split(".")[1].length}catch(e){}
  try{m+=s2.split(".")[1].length}catch(e){}
  return Number(s1.replace(".",""))*Number(s2.replace(".",""))/Math.pow(10,m);
}
//四舍五入保留两位小数(v的值是几保留几位小数)
function decimal(num,v){
    var vv = Math.pow(10,v);
    return Math.round(num*vv)/vv;
}

$num= bcmul(1, 0.123456789, 8); //0.12345678
备注bcmul(a, b，c)a，b代表数值，c则是运算后保留几位小数

$num = round($num, 2);//0.12