JavaScript: Validate whether a given value is number or not

Last update on March 06 2025 11:07:26 (UTC/GMT +8 hours)

JavaScript validation: Exercise-5 with Solution

Validate Number

Write a JavaScript function to validate whether a given value is a number or not.

Sample Solution:-

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript function to validate whether a given value is number or not.</title>
</head>
<body>

</body>
</html>

JavaScript Code:

function is_number(value)
        {
        return !isNaN(value) && toString.call(value) === '[object Number]';
       }

console.log(is_number(NaN));

console.log(is_number(42.32));

console.log(is_number(72));

Sample Output:

false
true
true

Flowchart:

Live Demo:

See the Pen javascript-validation-exercise-5 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

Write a JavaScript function that checks if a given value is of type number using typeof and verifies it is not NaN.
Write a JavaScript function that validates numeric input by using Number.isFinite() to ensure the value is a finite number.
Write a JavaScript function that distinguishes between numeric strings and actual numbers and returns appropriate results.
Write a JavaScript function that filters an array for values that are numbers and excludes all other types.

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