caller property in JavaScript

function displayArgLength()
    {
      var argLengthStr = "The calling function contained ";
      argLengthStr += arguments.caller.length;
      argLengthStr += " arguments.";
      alert(argLengthStr);
    }
    function myFunction()
    {
      var aString = arguments[0].value;
      aString += "'s is ";
      aString += arguments[1];
      alert(aString);
      displayArgLength();
    }