How to check if a string contains a number in JavaScript?

Question

I don\'t get how hard it is to discern a string containing a number from other strings in JavaScript.

Number(\'\') evaluates to 0, while

Answer 1

There's this simple solution :

var ok = parseFloat(s)==s;

If you need to consider "2 " as not a number, then you might use this one :

var ok = !!(+s==s && s.length && s.trim()==s);