jsx-eslint/eslint-plugin-react

Rule proposal: no layout thrashing

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#1,889 opened on Jul 20, 2018

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acceptedhelp wantednew rule

Description

I've seen a lot of seemingly simple code lead to layout thrashing and performance problems that could have been statically detected and avoided. It would be nice to have a rule that could flag some of these scenarios.

I think it might make sense to take Paul Irish's list of what causes layout/reflow, and write a rule that flags when these happen synchronously in places like componentDidMount, render, and componentWillReceiveProps, etc.

Example:

class Foo extends React.Component {
  constructor(props) {
    super(props);

    this.state = {
      windowHeight: window.innerHeight, // <-- this forces layout
    };
  }
  // ...
}

Thoughts?

Contributor guide

Tech stack
javascriptreact
Domain
frontendperformance
Issue type
performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
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.
mostly clear
Prerequisites
React lifecycleESLint rule structure
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
This issue proposes a new ESLint rule to detect layout thrashing in React components. To proceed, review Paul Irish's list of layout triggering properties and methods, and identify which are commonly used synchronously in lifecycle methods like componentDidMount and render. Consider existing similar rules in the plugin for pattern reference. The main challenge is determining when the reads are harmful; a static analysis approach would need to track reads that force layout. Look at the plugin's source code structure for adding a new rule.