isNumber javascript Code Snippet in 2025
typemathbeginner
Last Updated: 27 October 2025
Checks if the given argument is a number.
- Use
typeofto check if a value is classified as a number primitive. - To safeguard against
NaN, check ifval === val(asNaNhas atypeofequal tonumberand is the only value not equal to itself).
const isNumber = val => typeof val === 'number' && val === val;
isNumber(1); // true
isNumber('1'); // false
isNumber(NaN); // falsejavascript snippet similar to isNumber For You in October 2025
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