How to check if a text is all white space characters in client side?

Question

How to check if a user input text is all white space characters (space, tab, enter etc) in client side?

Answer 1

Josh's answer is very close to this, but according to w3schools (in May 2014) it is as follows:

function isEmpty(str) {
    return str.replace(/^\s+|\s+$/gm,'').length == 0;
}