charCodeAt to return correct code for custom charcodes
<p>Would this be good way to return correct code for custom charcodes</p>

<pre><code>String.prototype._charCodeAt = String.prototype.charCodeAt;
String.prototype.charCodeAt = function( i , keycodes ) {
    if( keycodes !== 'undefined' ) {
        for( var j = 0; j &lt; keycodes.length; j++ ) {
            if( this[i] === keycodes[j].char ) {
                return keycodes[j].code;
            }
        }
    } else {
        return this._charCodeAt( i );
    }
}
</code></pre>

<p>Keycodes is array where values stored like this</p>

<pre><code>[
    ...
    { "char" : "ä" , "code" : 132 },
    { "char" : "à" , "code" : 133 },
    { "char" : "å" , "code" : 134 },
    ...
];
</code></pre>

<p>By default the javascript returns wrong values for the "special characters".<br>
Is this code sufficient for this?</p>
