JavaScript: Round a number to a given specific decimal places

Last update on April 22 2023 12:19:41 (UTC/GMT +8 hours)

JavaScript Math: Exercise-14 with Solution

Write a JavaScript function to round a number to decimal place.

Test Data:
console.log(precise_round(12.375,2));
console.log(precise_round(12.37499,2));
console.log(precise_round(-10.3079499, 3));
Output :
"12.38"
"12.37"
"-10.308"

Pictorial Presentation:

$JavaScript: Math - Round a number to a given specific decimal places.$

Sample Solution:

HTML Code:

<!DOCTYPE html>
  <html>
  <head>
  <meta charset="utf-8">
  <title>Round a number to a given decimal places</title>
  </head>
  <body>
</body>
  </html>

JavaScript Code:

//Ref.https://bit.ly/3zxAhnH
function precise_round(n, r) {
    let int = Math.floor(n).toString()
    if (typeof n !== 'number' || typeof r !== 'number') return 'Not a Number'
    if (int[0] == '-' || int[0] == '+') int = int.slice(int[1], int.length)
    return n.toPrecision(int.length + r)
}
console.log(precise_round(12.375,2));
console.log(precise_round(-10.3079499, 3));
console.log(precise_round(10.49999,0));
console.log(precise_round(10.49999,2));

Sample Output:

Flowchart:

$Flowchart: JavaScript Math- Round a number to a given specific decimal places$

Live Demo :

See the Pen javascript-math-exercise-14 by w3resource (@w3resource) on CodePen.

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