angular/components

Changing the value of one progress bar repaints other progress bars on the same page

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#19,873 opened on Jul 6, 2020

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P4area: material/progress-barhelp wanted

Description

Reproduction

Use StackBlitz to reproduce your issue: https://stackblitz.com/edit/angular-dc63ug?file=src%2Fapp%2Fprogress-bar-determinate-example.html

Steps to reproduce:

  1. Open the url in latest chrome
  2. Open dev tool and click three dots, click more tools, add Rendering tab, select paint flashing checkbox there
  3. Now go back to demo url and change the value of second progress bar by typing in the second input box (from top)
  4. while changing any value you will observe the beneath progress bar is also repainting

Expected Behavior

What behavior were you expecting to see? Changing the value of one progress bar should not re-paint the other progress bar on the same page

Actual Behavior

What behavior did you actually see? Changing the value of one progress re-painting the other progress bar on the same page

Environment

  • Angular:8.2
  • CDK/Material:8.2.3
  • Browser(s): Chrome - 83.0.4103.116
  • Operating System (e.g. Windows, macOS, Ubuntu): Windows

Contributor guide

Tech stack
typescripthtmlcss
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Angular change detectionZone.js
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
The issue is reproducible in the provided StackBlitz. Investigate the progress bar component in `src/lib/progress bar/` directory. The repaint occurs because Angular's default change detection triggers updates on all progress bars when one changes. Consider using `OnPush` change detection or detaching change detection for individual progress bars.
Changing the value of one progress bar repaints other progress bars on the same page · angular/components#19873 | Good First Issue