angular: Angular 9.x Polyfills - Lighthouse Error - Does not use passive listeners to improve scrolling performance

🐞 bug report

Affected Package

Angular 9.x pollyfills

Is this a regression?

I am not sure, I previously had score of 100 on Lighthouse in Chrome Dev tools, but recently it started displaying this error when I run audit for the website. It could a regression or may be the new version of Lighthouse just started reporting it.

Description

When I run Audit for my website in Lighthouse in Chrome Dev tools, it displays below error:

Does not use passive listeners to improve scrolling performance

and points to pollyfills file (/polyfills-es2015.5715214….js(www.1eent.com) | line: 0)

🔬 Minimal Reproduction

Open chrome Dev Tools and in Audit tab, run audit for the website https://www.mustakbil.com once the audit is complete, you can view the error under Best Practices section.

🔥 Exception or Error


Does not use passive listeners to improve scrolling performance

/polyfills-es2015.5715214….js(www.1eent.com) | line: 0

🌍 Your Environment

Angular Version:


Angular CLI: 9.0.0-next.4
Node: 10.16.3
OS: win32 x64
Angular: 9.0.0-next.6
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... platform-server, router, service-worker

Package                                    Version
--------------------------------------------------------------------
@angular-devkit/architect                  0.900.0-next.4
@angular-devkit/build-angular              0.900.0-next.4
@angular-devkit/build-optimizer            0.900.0-next.4
@angular-devkit/build-webpack              0.900.0-next.4
@angular-devkit/core                       9.0.0-next.4
@angular-devkit/schematics                 9.0.0-next.4
@angular/cdk                               8.1.4
@angular/cli                               9.0.0-next.4
@angular/fire                              5.2.1
@angular/material                          8.1.4
@angular/pwa                               0.900.0-next.4
@ngtools/webpack                           9.0.0-next.4
@nguniversal/module-map-ngfactory-loader   8.1.1
@schematics/angular                        9.0.0-next.4
@schematics/update                         0.900.0-next.4
rxjs                                       6.5.2
typescript                                 3.5.3
webpack                                    4.39.3

Details about passive listeners can be found here https://developers.google.com/web/tools/lighthouse/audits/passive-event-listeners

About this issue

Original URL
State: closed
Created 5 years ago
Reactions: 2
Comments: 20 (14 by maintainers)

Most upvoted comments

This issue was related to matTooltip which has been fixed in https://github.com/angular/components/pull/17003.

Thank you so much @gkalpak and @patrickhulce for your time and help 😃

naveedahmed1 on Oct 1, 2019

Awesome! Thx for the update, @naveedahmed1 👍

gkalpak on Oct 1, 2019

That’s correct @naveedahmed1 it lists the currently active listeners in that pane.

I’m not able to see the non-passive touchstart listener in that panel even when I see the violation, so I’m guessing it’s removed at some point. This is a good point on possible adjustments to make in LH, so we’ll re-open that issue. Ideally, it’s still never added in the first place, but it’s not a cause for concern to the audit’s purpose 😃

Thanks for investigating all!

patrickhulce on Sep 30, 2019