Tricks in Internet Explorer JavaScript

Question

I have found one IE fix in this event libray, but there are not any comments with the exception of one note: 'ie fix';

What does this code do? For which ie this fix is needed?

 if (elem.setInterval && ( elem != window && !elem.frameElement ) ) {

  elem = window;

}

http://javascript.ru/files/event/event.js

Where did you find this? – Giacomo1968 May 27 '14 at 19:49 — Giacomo1968, May 27 '14 at 19:49
http://javascript.ru/files/event/event.js – user2754035 May 27 '14 at 19:52 — user2754035, May 27 '14 at 19:52

Jeremy J Starcher · Accepted Answer · 2014-05-28T03:38:55.267

Alright, I'll explain what is going on -- but it is kind of wonky.

  // This is a cheap duck test.  normally, only a "top level" object would contain
  // a setInterval property/method
  // By top level, that pretty much means a window, a frame, or an iframe.
  // So this is a lame/broken test for that.
  if (elem.setInterval

  && 

  // Then we check to see if we have a window or a frame.
  ( elem != window && !elem.frameElement ) ) {
    // If we don't have either, assume that we were passed something totally bogus
    // and assign this to the window value.
    elem = window;
  }

Without reading the API, I did look at the code. A far, far better way to write that would be closer to:

add: function(elem, type, handler) {
  if (elem === undefined) {
    elem = window;
  }

or, as I'd write it:

add: function(elem, type, handler) {
  // MUCH better test is shown here:
  // http://stackoverflow.com/questions/384286/javascript-isdom-how-do-you-check-if-a-javascript-object-is-a-dom-object

  if (elem === undefined) {
    throw "Event.Add warning. Must pass an element to bind the event to."
  }

Tricks in Internet Explorer JavaScript

1 Answers1