Common useful functions for JavaScript

common.js

var Common = {
  addEvent : function(ele, evType, fn, useCapture) {
    if (ele.addEventListener) { 
      ele.addEventListener(evType, fn, useCapture); 
      return true; 
    }else if (ele.attachEvent) { 
      var r = ele.attachEvent('on' + evType, fn); 
      return r; 
    }  else {
      ele['on' + evType] = fn;
    }
  },

  removeEvent : function(ele, evType, fn, useCapture) {
    if (ele.removeEventListener) { 
      ele.removeEventListener(evType, fn, useCapture); 
      return true; 
    }else if (ele.detachEvent) { 
      var r = ele.detachEvent('on' + evType, fn); 
      return r; 
    }  else {
      ele['on' + evType] = null;
    }
  },

  findPos : function(obj) {
    var curleft = 0;
    var curtop = 0;
    if (obj.offsetParent) {
      do {
        curleft += obj.offsetLeft;
        curtop += obj.offsetTop;
        } while (obj = obj.offsetParent);
        return [curleft,curtop];
    }
  },

  getScrollTop : function(){
    if(typeof pageYOffset!= 'undefined'){
      //most browsers except IE before #9
      return pageYOffset;
    }
    else{
      var B= document.body; //IE 'quirks'
      var D= document.documentElement; //IE with doctype
      D= (D.clientHeight)? D: B;
      return D.scrollTop;
    }
  },

//FROM: http://www.openjs.com/scripts/dom/class_manipulation.php
  hasClass : function(ele,cls) {
    return ele.className.match(new RegExp('(\\s|^)'+cls+'(\\s|$)'));
  },
   
  addClass : function(ele,cls) {
    if (! this.hasClass(ele,cls)) ele.className += " "+cls;
  },
   
  removeClass : function(ele,cls) {
    if (this.hasClass(ele,cls)) {
        var reg = new RegExp('(\\s|^)'+cls+'(\\s|$)');
      ele.className=ele.className.replace(reg,' ');
    }
  }
};