Question

25

Check if a variable contains a numerical value in Javascript?

rated 0 times [ 28] [ 3] / answers: 1 / hits: 27574 / 15 Years ago, sun, march 1, 2009, 12:00:00

In PHP, it's pretty easy:

is_numeric(23);//true

is_numeric(23);//true

is_numeric(23.5);//true

is_numeric(true);//false

But how do I do this in Javascript?
I could use a regular expression, but is there a function for this?

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answered 15 Years ago ishmaelw · Accepted Answer

What about:

function isNumber(n){

    return typeof(n) != boolean && !isNaN(n);

}

The isNaN built-in function is used to check if a value is not a number.

Update: Christoph is right, in JavaScript Boolean types are convertible to Number, returning the 1 for true and 0 for false, so if you evaluate 1 + true the result will be 2.

Considering this behavior I've updated the function to prevent converting boolean values to its numeric representation.