1.
  try {
      .....
     
    } catch (e) {
      e.description;
    }
   
2.object 
 a.common:
        getElementById(),getElementsByTagName,getElements,getElementsByClassName
  
        innerHTML, innerTEXT, type,tagName
  
        typeof (typeof element == 'object')
        if ((typeof o == "object") && (o.constructor == Date))

  
  b.event:
     srcElement (window.event.srcElement.parentElement)
     keyCode
 
3.
  parseInt()

4.
  arguments
  
5.getElementsByTagName
bod = document.getElementsByTagName('body')[0];