MooTools String.limitChars with 'preserve words' option, stolen from Kohana 3

String.limitChars.js

// Port of Kohana3's Text::limit_chars helper

String.implement({
	
	limitChars: function(limit, options){
		var opts = {
			endChar: null,
			preserveWords: false
		};
		$extend(opts, options);
		
		var endChar = (opts.endChar == null) ? '…' : opts.endChar;
		if (this.trim() === '' || this.length <= limit) return this;
		if (limit <= 0) return endChar;
		if (!opts.preserveWords) return this.substr(0, limit) + endChar;
		
		var pattern = new RegExp('^.{' + (limit-1) + '}\\S*');
		var matches = this.match(pattern);
		return matches[0].trim() + ((matches[0].length == this.length) ? '' : endChar);
	}
	
});