Ucwords for Javascript

PHP has a great function ucwords that uppercases the first character of each word in a string. So hello world becomes Hello World.

Javascript and jQuery are both missing this usefull function so I mashed together the below port of ucwords to javascript

ucwords.js

String.prototype.ucwords = function() {
    str = this.toLowerCase();
    return str.replace(/(^([a-zA-Z\p{M}]))|([ -][a-zA-Z\p{M}])/g,
        function($1){
            return $1.toUpperCase();
        });
}

Example usage:

var hello = 'HELLO world';
hello.ucwords();

This will convert HELLO world to Hello World, etc..

Note: A pure port of PHPs ucwords would remove the str = this.toLowerCase(); line so as leave capitalised words as it