Kendo UI and Passive Event Listeners

[Angelo]

Hello Telerik/Kendo People,

I have been noticing a certain lag in my application's responsiveness and using Chrome's developer tools to debug, I found out that the JS calls are being slowed with the following verbose console logs:

[Violation] Added non-passive event listener to a scroll-blocking 'touchstart' event. Consider marking event handler as 'passive' to make the page more responsive. See https://www.chromestatus.com/feature/5745543795965952

jquery-1.12.3.js:4932

The relevant SO question pointing to this is in this link: 

StackOverflow Question

Given jQuery is still in the implementation of a fix for this issue through their library, I wonder what Kendo recommends as a workaround for this issue.

Thanks.

 

[Dimitar]

Hello Angelo,

Can you provide a working Dojo example where the described performance issue can be observed? We can examine it locally and try to determine the origin of the issue.

In general, passive event listeners support is scheduled for the 4.0 release of jQuery (jQuery 4.0 Event Design). As Kendo UI is based on jQuery, the recommended approach is to wait for the next major release of jQuery (4.0) and the respective Kendo UI version.

Dimitar
Progress Telerik

[Andrew]

Hi Dimitar,

I presume that this is still the case 3 years on, and jQuery 4 is only 50% through it's road map we are unlikely to see this anytime soon.

Is there a suggested workaround?

Thanks,

Andy

[Dimitar]

Hi Andrew,

Support for passive event listeners is targeting the jQuery 4.0 release. I would suggest monitoring the official issue in the jQuery repository for additional information:

• https://github.com/jquery/jquery/issues/2871

In the above-linked thread there is a suggested workaround for passive event listener support that you could examine:

• https://github.com/jquery/jquery/issues/2871#issuecomment-497963776

Regards,
Dimitar
Progress Telerik