Element.truncate.js

Element.implement({

	// truncates element text to fit its width
	truncate: function(trail){
		var text = this.get('text').trim();
		if (!text) return;

		trail = trail || '...';
		var style = this.style;
		var styles = { overflow: style.overflow, 'white-space': style.whiteSpace, padding: style.padding, margin: style.margin };
		this.setStyles({ overflow: 'hidden', 'white-space': 'nowrap', padding: 0, margin: style.padding });
		var width = this.clientWidth;

		if (this.scrollWidth > width){

			text = text.split(/\s+/);
			var words = [];

			for (var i = 0; i < text.length; i++){
				words[i] = text[i];
				this.set('text', words.join(' ') + '_' + trail);
				if (this.scrollWidth > width) break;
			}

			words.pop();
			this.set('text', words.join(' ').replace(/[^A-z0-9]+$/, '') + trail);

		}

		return this.setStyles(styles);
	}

});