/* - - - - - - - - - - - - - - - - - - - - - - -
 checkEnter javascript
 - - - - - - - - - - - - - - - - - - - - - - - */

 function checkEnter(e){       //e is event object passed from function invocation
  var characterCode            // literal character code will be stored in this variable

  if(e && e.which){            //if which property of event object is supported (NN4)
    e = e
    characterCode = e.which    //character code is contained in NN4's which property
  }
  else{
    e = event
    characterCode = e.keyCode  //character code is contained in IE's keyCode property
  }

  if(characterCode == 13){     //if generated character code is equal to ascii 13 (if enter key)
    f1();
    return false
  }
  else{
    return true
  }
}