前端的四舍五入

var iTofixed =function(num,fractionDigits) {var arr,val,len,value;val=(Math.round(num*Math.pow(10,fractionDigits))/Math.pow(10,fractionDigits)+Math.pow(10,-(fractionDigits+1)))arr=val.toString().split('.');len=arr[0].length +Number(fractionDigits+1)value=val.toString().slice(0,len)return value};console.log(iTofixed(298561.7251679,4))//298561.7252