(link: https://www.jb51.net/article/154898.htm)

(link: https://www.jb51.net/article/154898.htm)

Here’s how to implement JavaScript with two decimal places: **rounded **The following results will be rounded:

var num =2.446242342;
num = num.toFixed(2); //  The output result is  2.45

**No rounding **The following processing results will not be rounded: First, round off the decimal:

Math.floor(15.7784514000 * 100) / 100
//  The output result is  15.77

The second, as a string, USES regular matching:

Number(15.7784514000.toString().match(/^d+(?:.d{0,2})?/))
//  The output result is  15.77, Cannot be used for integers such as  10  You must write to 10.0000

Note: if it is a negative number, convert it to a positive number and then calculate it

Javascript keeps instances of two decimal places:

<script type="text/javascript">
 //Keep two decimal places
 //Function: round floating point number to 2 decimal places
 function toDecimal(x) {
  var f = parseFloat(x);
  if (isNaN(f)) {
  return;
  }
  f = Math.round(x*100)/100;
  return f;
 }


 //The system retains two decimal places, such as: 2, which is followed by 00. That is, 2.00
 function toDecimal2(x) {
  var f = parseFloat(x);
  if (isNaN(f)) {
  return false;
  }
  var f = Math.round(x*100)/100;
  var s = f.toString();
  var rs = s.indexOf('.');
  if (rs < 0) {
  rs = s.length;
  s += '.';
  }
  while (s.length <= rs + 2) {
  s += '0';
  }
  return s;
 }

 function fomatFloat(src,pos){
  return Math.round(src*Math.pow(10, pos))/Math.pow(10, pos);
 }
 //rounded
 alert(" keep 2 Decimal places: " + toDecimal(3.14159267));
 alert(" Mandatory reserves 2 Decimal places: " + toDecimal2(3.14159267));
 alert(" keep 2 Decimal places: " + toDecimal(3.14559267));
 alert(" Mandatory reserves 2 Decimal places: " + toDecimal2(3.15159267));
 alert(" keep 2 Decimal places: " + fomatFloat(3.14559267, 2));
 alert(" keep 1 Decimal places: " + fomatFloat(3.15159267, 1));

 //Six into five shekels
 alert(" keep 2 Decimal places: " + 1000.003.toFixed(2));
 alert(" keep 1 Decimal places: " + 1000.08.toFixed(1));
 alert(" keep 1 Decimal places: " + 1000.04.toFixed(1));
 alert(" keep 1 Decimal places: " + 1000.05.toFixed(1));

 //Scientific count
 alert(3.1415.toExponential(2));
 alert(3.1455.toExponential(2));
 alert(3.1445.toExponential(2));
 alert(3.1465.toExponential(2));
 alert(3.1665.toExponential(1));
 //To n bits, no n bits
 alert(" Accurate to the decimal point 2 position " + 3.1415.toPrecision(2));
 alert(" Accurate to the decimal point 3 position " + 3.1465.toPrecision(3));
 alert(" Accurate to the decimal point 2 position " + 3.1415.toPrecision(2));
 alert(" Accurate to the decimal point 2 position " + 3.1455.toPrecision(2));
 alert(" Accurate to the decimal point 5 position " + 3.141592679287.toPrecision(5));
 </script>

Using Javascript to get a float to two decimal places, for example 22.127456 to 22.13, how to do?

1. Discard the decimals and keep the integers

ParseInt (5/2)

2. Round up, add 1 to the whole number if there are decimals

Math. Ceil (5/2)

3. Round.

Math. Round (5/2)

4, round down

Math. Floor (5/2)

Alternative approach

The stupidest way

function get()
{
    var s = 22.127456 + "";
    var str = s.substring(0,s.indexOf(".") + 3);
    alert(str);
}
 

2. Regular expressions work well

<script type="text/javascript">
onload = function(){
    var a = "23.456322";
    var aNew;
    var re = /([0-9]+.[0-9]{2})[0-9]*/;
    aNew = a.replace(re,"$1");
    alert(aNew);
}
</script>

He’s smarter…

<script>
var num=22.127456;
alert( Math.round(num*100)/100);
</script>

5. Js keep 2 decimal places (mandatory)

For decimal places larger than 2, the above function is fine, but for decimal places smaller than 2, such as changeTwoDecimal(3.1), will return 3.1.

function changeTwoDecimal_f(x) {
    var f_x = parseFloat(x);
    if (isNaN(f_x)) {
        alert('function:changeTwoDecimal->parameter error');
        return false;
    }
    var f_x = Math.round(x * 100) / 100;
    var s_x = f_x.toString();
    var pos_decimal = s_x.indexOf('.');
    if (pos_decimal < 0) {
        pos_decimal = s_x.length;
        s_x += '.';
    }
    while (s_x.length <= pos_decimal + 2) {
        s_x += '0';
    }
    return s_x;
}

Function: round the floating point number to 2 places after the decimal point. If there are less than 2 places, fill 0. This function returns the format usage of the string: changeTwoDecimal(3.1415926) returns 3.14 changeTwoDecimal(3.1) returns 3.10