cssinjs/jss

Styles created multiple times when using function values

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#1361 opened on Jul 3, 2020

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 (8 comments) (6 reactions) (0 assignees)JavaScript (7,000 stars) (434 forks)batch import
bughelp wantedimportantperf

Description

Expected behavior: Duplicate styles shouldn't be created.

Describe the bug: On every component render, in which useStyles prop changes, new duplicate styles are created. I've managed to reproduce the bug in Codesandbox. To see it:

  1. Open codesandbox link from below
  2. Inspect red text element and see styles applied
  3. Click on button few times to cause component re-render
  4. Inspect some another element on the page and the red text again.
  5. Notice duplicate styles The styles are duplicated only for elements styled with css selector. If you check styles on the element with container class, you'll see there is no duplication there.

Codesandbox link: https://codesandbox.io/s/react-jss-playground-7ftrs?file=/index.js

Versions (please complete the following information):

  • jss: 10.1.1
  • Browser [e.g. chrome, safari]: any
  • OS [e.g. Windows, macOS]: any

Contributor guide

Tech stack
javascriptreactcss
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.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
React basicsJSS library concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55
Research direction
Reproduce the bug using the provided codesandbox (https://codesandbox.io/s/react jss playground 7ftrs). Examine the JSS source code, particularly the style creation logic and handling of function values. Look at the `useStyles` hook and related files. Review comments in the issue for any suggested fixes or workarounds.