Asynchronous JS or Javascript invocation code?

[steve bullman]

I was advised by my developer to use Asynchronous JS for display ads, but it is considerably slower than using Javascript method. Whilst Javascript loads instantly, there is a clear second delay if I use JS. Is there a way to improve this?  

[Tim Vereecke]

Using Async JS should make the rest of the page (without the ads) load faster because rendering is not blocked while the JS snippet dowloads.

Are you seeing a delay in your ads? or also a delay of the page contents?

And what do you mean with considerable?

 

[steve bullman]

On 11/6/2022 at 3:18 PM, scalemates said:

 

And what do you mean with considerable?

 

See for yourself https://staging.arbtalk.co.uk/

 

[Tim Vereecke]

hi Steve,

When you test performance of asynchronous make sure to have ALL your zones using the asynchronous method.

The reason is:

• The asynchronous method sends the actual zone invocation request on DOMContentLoaded.
• However the synchronous version delays this DOMContentLoaded event.

This is also true when the async zone is before any sync zone (like seen in your screenshot) 

For example if on your PRD site you would add a single zone using asynchronous it would for synchronous zones to load which delay the yellow line (=DOMContentLoaded)

 

Edited March 14 by Tim Vereecke