How to check whether the input text field contains only white spaces?

Question

What is the easiest way to check in Javascript whether the input text field is empty (contains nothing or white spaces only)?

Answer 1

var str = document.getElementById("myInput").value;
if (str.match(/^\s*$/)) {
    // nothing, or nothing but whitespace
} else {
    // something
}

Answer 2

You are looking for something like trim function, right?

Answer 3

Include this function somewhere (in order to provide a trim function)

String.prototype.trim = function () {
   return this.replace(/^\s*(\S*(\s+\S+)*)\s*$/, "$1");
};

see here http://javascript.crockford.com/remedial.html

then...

if (document.forms['id_of_form'].elements['id_of_input'].value.trim()=='') {
    //do xyz
}