js保留两位小数不四舍五入

保留两位小数不四舍五入

    function retain(num,decimal){
        num = num.toString();
        let index = num.indexOf('.');
                if(index !== -1){
                    num = num.substring(0,decimal + index + 1)
                }else{
                    num = num.substring(0)
                }
                return parseFloat(num).toFixed(decimal) 
    }   
    var nums=retain(33.45678, 2); 
    console.log(nums) //33.45

function retain2(num,d){
    return (parseInt(num*100)/100).toFixed(d)
}
var nums=retain2(33.45678, 2);  
console.log(nums)//33.45

var num=Math.floor(15.7784514000 * 100) / 100 ; //15.77
console.log(typeof num)  //number