CODEWITHSUNDEEP
javascript
vpp090
vpp090

Reputation: 1073

How to round a number in JavaScript only if necessary

I want to round a number in JavaScript but to 2 decimal places but only if necessary.

For example 4.5 to be 4.50 and 3.331 to be 3.331.

I have tried using Math.round(number / 100) * 100 but when number is 4.5 it gives me 4.5 and I want it to be 4.50.

I have tried using .toFixed(2), but when number is 3.331 it will fix it to 3.33.

Any help is much appreciated.

Upvotes: 1

Views: 716

Answers (4)

Phyrum Tea
Phyrum Tea

Reputation: 2653

This looks like an String format and not a rounding problem:

var value = 4 + '.';
var [num, dec] = value.split('.');

if (dec.length < 2) {
  dec = (dec + '00').substring(0, 2);
}
console.log(`${num}.${dec}`);

Runnable snippet:

function format(value) {
  var [num, decimal] = (value + '.').split('.');
  
  if (decimal.length < 2) {
    decimal = (decimal + '00').substring(0, 2);
  }

  return `${num}.${decimal}`;  
}

console.log([4, 4.5, 3.331].map(format));

4 -> 4.00

4.5 -> 4.50

3.331 -> 3.331

Upvotes: 0

Janie
Janie

Reputation: 646

Using regex check the digits after the dot. if it is less than 2 then use toFixed(2), else do nothing.

function f(n) {
    let diff = Number(n) - Math.floor(Number(n));
    return /\.[0-9]{2,}/.test(diff.toString()) ? n : n.toFixed(2)
}
const nums = [3.331, 2.5, 3].map(f)
console.log(nums)

Upvotes: 1

Mos&#232; Raguzzini
Mos&#232; Raguzzini

Reputation: 15821

You can try to apply conditionallu toFixed() method:

const numbers = [4.5, 3.331];
const floated = numbers.map(
  n => {
    const floatLen = n.toString().split('.')[1];
    if(floatLen){
      if(floatLen.toString().length < 2){
        return n.toFixed(2);
      }
    }
  return n;
  }
);
console.log(floated);

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386560

You could check if the fixed value change and select the kind of formatting.

function format(f) {
    return f === +f.toFixed(2)
        ? f.toFixed(2)
        : f.toString()
}

console.log([4.5, 3.331, 3].map(format));

Upvotes: 3

Related Questions