jsx-eslint/eslint-plugin-react

Rule proposal: disallow onFocusIn and onFocusOut on DOM element tags

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#714 opened on Jul 26, 2016

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help wantednew rule

Description

React will issue a warning in dev if you use onFocusIn or onFocusOut.

https://github.com/facebook/react/blob/85dcbf83/src/renderers/dom/shared/ReactDOMComponent.js#L196-L200

This should be easy enough to enforce for most cases with a linter rule.

Bad:

<div onFocusIn={() => {}} />

<div onFocusOut={() => {}} />

Good:

<div onFocus={() => {}} />

<div onBlur={() => {}} />

Contributor guide

Tech stack
javascriptreact
Domain
tooling
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
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
ESLint plugin developmentReact event handling
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80
Research direction
Examine the React source code link in the issue to understand the warning. The rule should detect onFocusIn and onFocusOut attributes on JSX DOM elements (lowercase tag names). Check existing rules in the eslint plugin react repository for patterns on how to implement similar attribute restrictions. The issue has a single comment but no additional context from maintainers, so the scope is well defined.