Element.truncate.js

Element.implement({
  /**
  truncates element text to fit in element width.
    end (bool) defaults false. True = cuts string at end, False = cuts string in middle
    str (string) truncation string default : '...'
  **/
  truncate : function(end,str){
    str = str || '...';
    var style = this.style;
    var originalStyles = { overflow: style.overflow, 'white-space': style.whiteSpace, padding: style.padding };
    this.setStyles({ overflow: 'hidden', 'white-space': 'nowrap', padding: 0 });
    var width = this.clientWidth;
   var txt = this.get('text');
    if(end){
      var rside = txt.length;
      while(this.scrollWidth > width){
        rside--;
        this.set('text',txt.slice(0,rside)+str);
      }
    } else {
      var mid = lside = Math.floor(txt.length / 2); var rside = lside+1;
      while(this.scrollWidth > width){
        ((mid-lside) < (rside-mid)) ? lside-- : rside++;
        this.set('text',txt.slice(0,lside)+str+txt.slice(rside));
      }
    }
    return this.setStyles(originalStyles);
  }
});