If condition load external javascript script

Question

I have the following DIV:

<div id="top-ad"></div>

I want to load an external advertisement javascript script if the browser size is higher than 728. So, I need something like this:

<div id="top-ad">
     <script>
     if(window.innerWidth >= 728) {
        <script src="//go.*****.com/?id=****"></script>
     }
     </script>
</div>

Of course the above won't work. I tried to load the script asynchronously using Jquery like this:

<div id="top-ad">
     <script>
     if(window.innerWidth >= 728) {
        $.getScript("//go.*****.com/?id=****");
     }
     </script>
</div>

I tried the above method but I get the following error:

Failed to execute 'write' on 'Document': It isn't possible to write into a document from an asynchronously-loaded external script unless it is explicitly opened.

I don't have access to the DOM elements inside the loaded script and they are actually dynamic and I'm not allowed to alter them. Is there a way to load the script inside the div element based on the if condition?

@NiettheDarkAbsol It is very bad practice to append scripts like that. — , Aug 27 '16 at 11:49
@SoftwareEngineer171 It is, I agree, but the script being appended itself uses `document.write` (as shown by the error message), so the only way to make that ad network's script work is to `document.write` it in. — Niet the Dark Absol, Aug 27 '16 at 11:50

score 4 · Accepted Answer · edited May 23 '17 at 12:22

4

Since the script you're loading uses document.write(), you have to use document.write to add the script in your if statement.

if (window.innerWidth >= 728) {
    document.write('<script src="//go.*****.com/?id=****"></sc' + 'ript>');
}

Notice that you have to split up </script>, otherwise it will end the <script> tag that runs your script. See Why split the <script> tag when writing it with document.write()?

edited May 23 '17 at 12:22

Community

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answered Aug 27 '16 at 11:53

Barmar

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I have also another question, by splitting the closing `script` tag like this, doesn't the tag get broken? – Michael Samuel Aug 27 '16 at 12:08
No, because the concatenation puts it back together, so it's not broken when `document.write()` adds it to the document. – Barmar Aug 27 '16 at 12:13
@MichaelSamuel I've added a link to a question that explains it. – Barmar Aug 27 '16 at 12:14

If condition load external javascript script

1 Answers1