jsx-eslint/eslint-plugin-react

warn when using setState in constructor

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#2371 opened on Aug 5, 2019

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 (3 comments) (0 reactions) (0 assignees)JavaScript (8,630 stars) (2,797 forks)batch import
acceptedhelp wantednew rule

Description

Obviously it could have been used by functions called from the constructor, but using setState in constructor is always an issue in react and causes a warning in debug mode.

Contributor guide

Tech stack
javascriptreact
Domain
toolingdeveloper experience
Issue type
feature
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.
half day
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 basicsESLint rule creation
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
The issue requests a warning when setState is called directly inside a constructor. Research existing rules in the eslint plugin react repo, such as no unused state, for implementation patterns. The new rule should traverse AST nodes to identify constructors (e.g., ClassBody with MethodDefinition kind 'constructor') and detect CallExpression to setState. Consider also tracking calls to functions invoked from the constructor. Review the 3 comments on the issue for additional context or pitfalls. Then implement the rule in a new file under rules/ and add tests.