JS error if LoadOn="ContentLoad.Init"

Question

This error appears randomly and tabs stops showing only if LoadOn="ContentLoad.Init" :

ejs.interop.min.js:1 Cannot use 'in' operator to search for '__eventList' in null

TypeError: Cannot use 'in' operator to search for '__eventList' in null

at Function.e.addOrGetEventData (https://cdn.syncfusion.com/ej2/17.4.49/dist/ej2.min.js:10:502006)

at Function.e.clearEvents (https://cdn.syncfusion.com/ej2/17.4.49/dist/ej2.min.js:10:502610)

at t.itemsAlign (https://cdn.syncfusion.com/ej2/17.4.49/dist/ej2.min.js:10:2554023)

at t.renderItems (https://cdn.syncfusion.com/ej2/17.4.49/dist/ej2.min.js:10:2571337)

at t.renderControl (https://cdn.syncfusion.com/ej2/17.4.49/dist/ej2.min.js:10:2553349)

at t.render (https://cdn.syncfusion.com/ej2/17.4.49/dist/ej2.min.js:10:2552667)

at t.appendTo (https://cdn.syncfusion.com/ej2/17.4.49/dist/ej2.min.js:10:520607)

at Object.invokeEJS (https://cdn.syncfusion.com/ej2/17.4.49/dist/ejs.interop.min.js:1:4226)

at http://localhost:53642/PerfectWeek/_framework/blazor.server.js:8:31421

at new Promise (<anonymous>)

ejs.interop.min.js:1 Cannot read property 'querySelector' of null

TypeError: Cannot read property 'querySelector' of null

at B (https://cdn.syncfusion.com/ej2/17.4.49/dist/ej2.min.js:10:5345)

at t.headerReady (https://cdn.syncfusion.com/ej2/17.4.49/dist/ej2.min.js:10:2615830)

at Object.invokeMethod (https://cdn.syncfusion.com/ej2/17.4.49/dist/ejs.interop.min.js:1:9856)

at http://localhost:53642/PerfectWeek/_framework/blazor.server.js:8:31421

at new Promise (<anonymous>)

throwError @ ejs.interop.min.js:1

invokeMethod @ ejs.interop.min.js:1

Alagumeena Kalaiselvan · Answer

Hi Andrey, Thanks for contacting Syncfusion support! We have validated your reported issue “_eventList in null” and validated by set the tab content loading type as “Init” but unfortunately we could not replicate the reported issue at our end. Also, we have prepared a sample based on your requirement. Refer below code for that @using Syncfusion.EJ2.Blazor.Navigations You can download this sample by the following link https://www.syncfusion.com/downloads/support/forum/151474/ze/TabComponent1644281918 Try to share below details which may helpful to proceed further on this Share issue replicating scenario Whether you have used our latest package version or not? Replicate your issue with shared sample Kindly let us know with above details to assist you earlier Regards Alagumeena.K

Steven Littleford · Answer

Andrey,Just so you are aware - i also have the tab control not appearing intermittently. I raise a ticket as a full paying customer and they have cut and pasted their response to me here as i pointed them to your post in support of mine. They have not done enough investigation on this. I spend 4 hours today trying to work out what is going on - clearly more then they have. I will keep working on this and will let  you know if i find the answer.cheersSteve

Steven Littleford · Answer

I can confirm that i am getting this exact error as well when the TAB does not display.

my initial findings today are that their is some sort of limit to how many controls can be pre-loaded.

I have a page that is consistently failing, however if i slowly remove controls then eventually the tab will appear.

Mr Andrey Voronov · Answer

In my environment each tab has 50 controls but nevertheless all tabs are always displayed when page loaded for the first time.But TABS stops showing after third navigation to the page

Steven Littleford · Answer

We managed to create a small project that replicated the issue.

Using that the Dev guys have managed to find the issue and are correcting it.

I wont know how fast they can get a fix to us until tonight

Cheers

Steve

Alagumeena Kalaiselvan · Answer

Dear customer, 

We have checked with your case by loading multiple controls inside Tab and we could able to replicate your reported issue “_eventList in null” at our end. We have considered this as defect and logged the defect report at our end and the fix will be included in our weekly release on February 25, 2020. Kindly be patience until then. 
 
https://www.syncfusion.com/feedback/12076/when-tab-content-as-init-and-loaded-with-multiple-components-the-tab-fails-to-load 

Regards 
Alagumeena.K

Mr Andrey Voronov · Answer

This error has not been fixed in 17.4.51 release.

Form shown properly on the first load, but on the second refresh no tabs are shown:

Cannot read property 'querySelector' of null

TypeError: Cannot read property 'querySelector' of null

at B (https://cdn.syncfusion.com/ej2/17.4.51/dist/ej2.min.js:10:5345)

at t.headerReady (https://cdn.syncfusion.com/ej2/17.4.51/dist/ej2.min.js:10:2615947)

at Object.invokeMethod (https://cdn.syncfusion.com/ej2/17.4.51/dist/ejs.interop.min.js:1:9980)

at http://localhost:53642/_framework/blazor.server.js:8:31421

at new Promise ()

Steven Littleford · Answer

Yep - same.

The sample i sent failed on the first load with the error, but since then has been working consistently.

So, they did fix something but it is not working in my application on pages with lots of controls. I have one page that ALWAYS gets the error.

I will send that in hope that the clue is there.

I have to say that i have spent the last two month since 17.4.39 working around issues and debugging issue for them that came out of that release. It is literally the worse release i have ever seen from any vendor and i am seriously starting to regret using this tool set.

Steven Littleford · Answer

ok - sounds stupid but try clearing cache. i just did and my tabs are now working....I have no idea why...

Mr Andrey Voronov · Answer

I cleared Chrome settings and can confirm that tabs are now work properly

Alagumeena Kalaiselvan · Answer

Dear customer, 

We are happy that your issue has been fixed and we recommended you whenever the NuGet package has been upgraded, it is need to clear the browser cache and NuGet cache to avoid that kind of problems. 

Kindly get back to us, If you need further assistance. 

Regards 
Alagumeena.K