JS loading script error

Question

I load external scripts to my site with this code:

 var script = document.createElement('script');
 script.type = 'text/javascript';
 script.src = 'http://example.com/script.js';
 document.getElementsByTagName("head")[0].appendChild(script);

It works, but how to check, if it was an error at the loading? For example timeout, or a server error.

In case you are open to using jQuery you can use .getScript which has built-in error and success handling: api.jquery.com/jQuery.getScript — m90
– m90, Commented Mar 25, 2012 at 14:18
Maybe this will be helpful to you stackoverflow.com/questions/3248384/… — Philipp Braun
– Philipp Braun, Commented Mar 25, 2012 at 14:20

Checksum · Accepted Answer · 2012-03-26 02:12:04Z

9

You can use the script.onerror to do something when there is an error loading it.

script.onerror = function() {
   alert("cannot load script");
}

document.getElementsByTagName("head")[0].appendChild(script);

Make sure you do it before you attach the script to the document

edited Mar 26, 2012 at 2:12

answered Mar 25, 2012 at 14:21

Checksum

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1 Comment

Checksum Over a year ago

You will need to declare the onerror handler before you attach it to the document. Updated my answer to reflect the same

Niet the Dark Absol · Accepted Answer · 2012-03-25 14:20:44Z

3

You can set onload (and possibly onerror - I've only used onload myself) on the script object before appending it to the document. The event will fire when the script loads successfully (or not, for onerror).

answered Mar 25, 2012 at 14:20

Niet the Dark Absol

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Comments

Joseph · Accepted Answer · 2012-03-25 15:09:38Z

2

DEMO

//check if script was loaded
script.onload = function() {
    alert('loaded');
}

//check if it didn't load
script.onerror = function() {
    alert('foo!');
}

edited Mar 25, 2012 at 15:09

answered Mar 25, 2012 at 14:23

Joseph

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1 Comment

Mi-La Over a year ago

Demo doesn't work when downloading nonexisten script from a valid address - e.g. script.src = 'apis.google.com/js/authNONEXISTENT.js' Only loaded is fired then.

Nik · Accepted Answer · 2012-03-25 14:18:18Z

-1

If you own the script you're referring to, get it to call a function in the calling page to say its ready. Alternatively you could check for existence of some object that's declared in that script you're loading.

answered Mar 25, 2012 at 14:18

Nik

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