Why doesn’t Mootools have a String.truncate() method?

I need a quick way to truncate strings! I’m surprised that neither MooTools’ String.js or String.Extras.js has such a method.  They have so many super-awesome functions, methods and extensions (I especially love the Date.js extensions!!).  Yeah, I really love mootools, and I feel compelled to share with the community.  So anyway, I wrote out a simple, straightforward String.truncate() function:

String.implement({
    /**
     * String.truncate(max, atChar, trail)
     *
     * ++All parameters are optional.
     * @param max = (integer) maximum length of truncated string. Defaults to 100 chars.
     * @param atChar = (string) truncate at the last index of this string. If not found, just truncates to max length.
     *                 If null, does not search and truncates to max length.
     * @param trail = (string) what you want appended to the end of the returned string
     *
     * @author Michael Fuery, Fuery Solutions, Inc. http://www.fuerysolutions.com/
     *
     * +Requires MooTools Core 1.2.2
     */
    truncate:function(max, atChar, trail){
        var s = this.trim();
        if(s.length<1) return '';
        if(!$defined(max)) var max = 100;
        else max = max.toInt();
        if(!$defined(atChar)) var atChar=' '; // break at space
        else if(atChar == null) var atChar=false;
        if(!$defined(trail)) var trail = '...';
 
        if(s.length > max) {
            var i=0;
            s = s.slice(0,max);
            if(atChar){
                if((i = s.lastIndexOf(atChar)) != -1){
                    s = s.substring(0, i);
                }else{
                    s = s.substring(0, max);
                }
            }
 
            s += trail;
        }
 
        return s;
    }
});