Check if a variable contains a numerical value in Javascript?

Question

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?

Answer 1

This checks for numerical values, including negative and floating point numbers.

function is_numeric(val){
    return val && /^-?\d+(\.\d+)?$/.test(val + '');
}

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@Vordreller: I corrected the Regex. It should work properly now.

Answer 2

function is_numeric(val) {
  return ((+val) == val);
}

That should do the trick.