TypeError: childAnchorTags.forEach is not a function
Closed, InvalidPublicPRODUCTION ERROR
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Assigned To

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Authored By

	phuedx
	May 20 2021, 3:51 PM

Description

Error

reqId: 8f23cf2b-e5ad-4a8e-a00a-cdfb5ce9ff31
Find reqId in Logstash

normalized_message

TypeError: childAnchorTags.forEach is not a function

exception.trace

at MutationObserver.observe.attributes  <anonymous>:1:3808

Impact

There have been ~70 such errors in the last 12 hours.

Notes

AFAICT all such errors are from clients with the following UA:

Mozilla/5.0 (Linux; Android 6.0; Le X509 Build/DHXOSOP5801911241S ) AppleWebKit/537.36 (KHTML, like Gecko) JioBrowser/1.4.7 Chrome/49.0.2623.91 Mobile Safari/537.36

i.e. Jio Browser running on an LeTv Le 1s

Supporting the above, neither MediaWiki code search nor Global Search return (relevant) results

Related Objects

Mentioned In: T298911: Consider checking for NodeList.prototype.forEach as part of Grade A support or providing a polyfill
Blog Post: Production Excellence #32: May 2021
Mentioned Here: T128115: Drop support for ES3 javascript browsers in MediaWiki

Event Timeline

phuedx created this task.May 20 2021, 3:51 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptMay 20 2021, 3:51 PM

Chrome/49.0.2623.91 does not support ES5 and forEach is an ES5 function. Given no matches on global search and mediawiki code search I tend to ignore these (by filtering on user agent) on the assumption they will go away when we support ES5 everywhere.

Decline?

(Removed Instrument-ClientError as that's used for issues in the instrumentation and this doesn't seem to be that)

https://logstash.wikimedia.org/app/dashboards#/doc/logstash-*/logstash-2021.05.24?id=tbDunXkB3UDnvh-Q667g
Likely code injected by Airtel ISP.

In T283252#7107859, @Jdlrobson wrote:

Given no matches on global search and mediawiki code search I tend to ignore these (by filtering on user agent) on the assumption they will go away when we support ES5 everywhere.

That happened in 2017 (T128115). Given it has no matches in our code bases, our startup feature test doesn't affect whether this third party code runs or not.

Also, the fact that our instrumentation is running in this Chrome 49 browser means it did pass our startup feature test. Chrome 49 is ES5-compliant, and does support Array.forEach. The problem is most likely not whether forEach exists, but rather whether their childAnchorTags variable holds an array or not.

Krinkle mentioned this in Blog Post: Production Excellence #32: May 2021.Jun 21 2021, 1:31 AM

Jdlrobson mentioned this in T298911: Consider checking for NodeList.prototype.forEach as part of Grade A support or providing a polyfill.Jan 10 2022, 8:43 PM

TypeError: childAnchorTags.forEach is not a functionClosed, InvalidPublicPRODUCTION ERRORActions