Javascript checking whether a variable is undefined

Question

To check whether adsense script is loaded or not, I use this:

var isAdsenseNotLoaded = (typeof adsbygoogle.loaded === 'undefined');

But from many users has this error in stack trace:

ReferenceError: adsbygoogle is not defined
    at http://example.com/file.js:1:42020

So should I also check whether adsbygoogle and also adsbygoogle.loaded ?

Duplicate of [this](http://stackoverflow.com/questions/5113374/javascript-check-if-variable-exists-is-defined-initialized-which-method-is-b)? — Paolo Gibellini, Aug 06 '15 at 12:38
@Paolo Not quite - tha'ts adressing a single variable, rather than a nested property — James Thorpe, Aug 06 '15 at 12:39
The operation should be applied to all the interested elements. See the answers — Paolo Gibellini, Aug 06 '15 at 12:42

Patsy Issa · Accepted Answer · 2015-08-07T09:30:53.023

11

You need to check if adsbygoogle is defined first:

var isAdsenseNotLoaded = !adsbygoogle || typeof adsbygoogle.loaded === 'undefined';

edited Aug 07 '15 at 09:30

answered Aug 06 '15 at 12:38

Patsy Issa

I suppose first part will be `adsbygoogle == false` or similar thing ? Because I need to check whether adsense is not loaded. – trante Aug 06 '15 at 16:50
@trante updated, missed the Not in `isAdsenseNotLoaded` – Patsy Issa Aug 07 '15 at 09:31
This does not work. when adsbygoogle is undefined it doesn't do anything. I tried alert(isAdsenseNotLoaded); only works when the object is defined. – dryleaf Jul 20 '18 at 04:15

score 1 · Answer 2 · edited May 23 '17 at 12:29

1

Yes, check for typeof adsbygoogle first, this will return if the global variable adsbygoogle is loaded.

var isAdsenseNotLoaded = (typeof adsbygoogle === 'undefined' || typeof adsbygoogle.loaded === 'undefined');

Checking for global variables with typeof will never produce any exceptions due to trying to access an undefined variable. Reference: JavaScript check if variable exists (is defined/initialized)

edited May 23 '17 at 12:29

Community

answered Aug 06 '15 at 12:40

Liglo App

This does not work. when adsbygoogle is undefined it doesn't do anything. I tried alert(isAdsenseNotLoaded); only works when the object is defined. – dryleaf Jul 20 '18 at 04:15

score 0 · Answer 3 · answered Aug 06 '15 at 12:40

0

So the whole object is not defined

var isAdsenseNotLoaded = (typeof adsbygoogle === 'undefined' || typeof adsbygoogle.loaded === 'undefined');

Just check in the first step if the object exists and then if it is loaded.

answered Aug 06 '15 at 12:40

Wa Kai

This does not work. when adsbygoogle is undefined it doesn't do anything. I tried alert(isAdsenseNotLoaded); only works when the object is defined. – dryleaf Jul 20 '18 at 04:14

3 Answers3