保留指定位数(四舍五入)
// 返回保留指定小数位四舍五入后的值(小数位不足时补0)(当其保留0位小数时,会四舍五入取整,eq:6.5 => 7)
function retainDecimal(number, i) {
let divisor = Math.pow(10, i);
number = Math.round(number * divisor) / divisor;
if (i == 0) {
return number;
}
let str = number.toString();
let index = str.indexOf(".");
if (index < 0) {
index = str.length;
str += ".";
}
while (str.length <= index + i) {
str += "0";
}
return str;
}