Registry / testing / eslint-plugin-flowtype

eslint-plugin-flowtype

library8.0.3jsnpmunverified

ESLint plugin providing Flow type linting rules. Current stable version is 8.0.3, released October 2021. It adds over 40 rules specific to Flow type annotations, such as enforcing type styles, preventing duplicates, and requiring type declarations. Key differentiators: it is the primary ESLint plugin for Flow, with extensive rule coverage and shareable configs. It requires ESLint 8+ and Node 12+. Maintenance is active but may slow as Flow usage declines. Alternative: use TypeScript with `@typescript-eslint` instead.

testing

npm install eslint-plugin-flowtype

github ↗package ↗

INSTALL

IMPORT

SIG · ESLINT-PLUGIN-FLOW

eslint-plugin-flowtype

testingjavascriptv8.0.3

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

plugin

✓ // In .eslintrc: 'plugins': ['flowtype']

✗ plugins: ['eslint-plugin-flowtype']

ESLint automatically adds prefix; just use 'flowtype'.

rules

✓ // In .eslintrc: 'rules': { 'flowtype/boolean-style': 'error' }

✗ rules: { 'boolean-style': 'error' }

Rules must be prefixed with 'flowtype/'.

configs

✓ // In .eslintrc: 'extends': ['plugin:flowtype/recommended']

✗ extends: ['eslint-plugin-flowtype/recommended']

Use plugin: prefix for shareable configs.

Installation and basic ESLint configuration with recommended rules and a simple Flow-annotated function.

// Install: npm install --save-dev eslint eslint-plugin-flowtype @babel/plugin-syntax-flow @babel/plugin-transform-react-jsx // .eslintrc.json { "plugins": ["flowtype"], "extends": ["plugin:flowtype/recommended"], "rules": { "flowtype/boolean-style": [2, "boolean"], "flowtype/define-flow-type": 1, "flowtype/delimiter-dangle": [1, "never"], "flowtype/generic-spacing": [1, "never"], "flowtype/no-mixed": 2, "flowtype/no-primitive-constructor-types": 2, "flowtype/no-weak-types": 2, "flowtype/object-type-delimiter": [1, "comma"], "flowtype/require-parameter-type": 2, "flowtype/require-return-type": [2, "always", { "annotateUndefined": "never" }], "flowtype/require-valid-file-annotation": 2, "flowtype/semi": [1, "always"], "flowtype/space-after-type-colon": [1, "always"], "flowtype/space-before-generic-bracket": [1, "never"], "flowtype/space-before-type-colon": [1, "never"], "flowtype/type-id-match": [2, "^([A-Z][a-z0-9]+)+Type$"], "flowtype/union-intersection-spacing": [1, "always"], "flowtype/use-flow-type": 1, "flowtype/valid-syntax": 1 } } // Example .js file with Flow // @flow function square(n: number): number { return n * n; }

Debug

Known issues

breakingv8.0.0 drops support for ESLint v7 and Node v10.

fix

Upgrade to ESLint 8+ and Node 12+.

affects: >=8.0.0

breakingv6.0.0 contains potentially breaking dependency updates.

fix

Review changelog for full list of updated dependencies.

affects: >=6.0.0 <7.0.0

deprecatedv7.0.0 dropped Node v10 support.

fix

Use Node >=12.

affects: >=7.0.0 <8.0.0

gotchaAdding 'eslint-plugin-flowtype' as plugin name will not work.

fix

Use 'flowtype' without prefix.

affects: >=4.0.0

gotchaRules must be prefixed with 'flowtype/' in rule configuration.

fix

Use 'flowtype/rule-name' instead of just 'rule-name'.

affects: >=1.0.0

Errors

Common errors & fixes

Error: Failed to load plugin 'flowtype' - Cannot find module 'eslint-plugin-flowtype'

Missing eslint-plugin-flowtype dependency

fix

npm install --save-dev eslint-plugin-flowtype

Error: ESLint configuration in .eslintrc.json is invalid: "plugins" must be an array

Wrong format for plugins field

fix

Use 'plugins': ['flowtype']

Error: Cannot find module '@babel/plugin-syntax-flow'

Missing peer dependency

fix

npm install --save-dev @babel/plugin-syntax-flow @babel/plugin-transform-react-jsx

Upgrade

Version history

8.0.3latest on npm

Audit

Dependencies

eslintrequiredpeer dependency; plugin works as an ESLint plugin

@babel/plugin-syntax-flowrequiredpeer dependency; required for parsing Flow syntax with Babel

@babel/plugin-transform-react-jsxoptionalpeer dependency; required for React JSX support when using Flow

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/gajus/eslint-plugin-flowtype ↗

packagehttps://www.npmjs.com/package/eslint-plugin-flowtype ↗