facebook/flow

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Adds static typing to JavaScript to improve developer productivity and code quality.

Stars: 22.3k
Forks: 1.9k
Open beginner issues: 0
Indexed issues: 510

Dominant language: Rust
License: MIT
Last GitHub push: Sep 15, 2026
Latest indexed: Sep 15, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: good first issue help wanted
PR merge metrics: No merged PRs in 30d

Open All

510 open issues indexed

Refinement seems to fail with opaque type aliases Open

Typing: opaque types Typing: refinements

facebook/flow#5753 · 0 comments · 2 reactions · 0 assignees · Indexed Sep 15, 2026
Why does a guard with a optional param doesn't work if reassigned? Open

facebook/flow#5755 · 11 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
type checks not took in consideration if stored in variable Open

facebook/flow#5757 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Flow do NOT check expression in JSX attr with namespace Open

facebook/flow#5769 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Type guard not considered for unreachable code Open

feature request

facebook/flow#5770 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Interface extending Array loses all type safety Open

bug

facebook/flow#5772 · 3 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
opaque flow string type dropped in for-in loop Open

Typing: opaque types

facebook/flow#5777 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Checks against an opaque type's subtype type fail to properly filter that type out Open

Typing: opaque types

facebook/flow#5794 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Flow fails to handle simple destructuring syntax Open

destructuring

facebook/flow#5822 · 2 comments · 5 reactions · 0 assignees · Indexed Sep 15, 2026
ElementConfig and destructuring assignment Open

Typing: unions/intersections

facebook/flow#5843 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Generic composition of two generic functions produces a non-generic composed function Open

Typing: polymorphism

facebook/flow#5847 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Feature: Turn off lint feature "const_params" with inline comments just like other linter rules Open

enhancement

facebook/flow#5868 · 3 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Flow can't seem to choose between union types Open

Typing: refinements Typing: tuple

facebook/flow#5873 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
flow CLI autocomplete command and get-def command doesn't recognize methods and properties of an object that starts with "$" ( dollar char ) Open

autocomplete get-def

facebook/flow#5906 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
"return this" from inherited method not working as expected Open

facebook/flow#5925 · 7 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Intersection of types with optional fields is incorrect Open

Typing: unions/intersections

facebook/flow#5929 · 2 comments · 2 reactions · 0 assignees · Indexed Sep 15, 2026
"Cannot resolve module" error could be more helpful Open

documentation error messages

facebook/flow#5935 · 4 comments · 50 reactions · 0 assignees · Indexed Sep 15, 2026
Feature request: refining multiple disjoint unions Open

feature request

facebook/flow#5948 · 4 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Problem creating elements when a prop is an intersection type Open

facebook/flow#5958 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Flow doesn't work with Lerna when importing packages into one another Open

facebook/flow#5975 · 7 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
check-contents doesn't include "unused suppression comment" Open

facebook/flow#5977 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Refinement of optional properties should use the `in` operator (and know a property is present, even if potentially null) Open

facebook/flow#6004 · 0 comments · 2 reactions · 0 assignees · Indexed Sep 15, 2026
Feature request: User-defined type assertions Open

feature request

facebook/flow#6052 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Composing multiple HOCs that return ComponentTypes using ElementConfig breaks prop types Open

facebook/flow#6057 · 13 comments · 19 reactions · 0 assignees · Indexed Sep 15, 2026
Inconsistent handling of Intersection of Objects when destructuring Open

facebook/flow#6071 · 0 comments · 3 reactions · 0 assignees · Indexed Sep 15, 2026
Union types are not applied on properties Open

bug regression Typing: unions/intersections

facebook/flow#6085 · 5 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
node_modules give errors in Windows and not Linux/Mac OS Open

Windows support

facebook/flow#6086 · 4 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Missing React.Component getDerivedStateFromProps definition Open

Library definitions react

facebook/flow#6101 · 0 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Missing React.Component getSnapshotBeforeUpdate definition Open

Library definitions react

facebook/flow#6104 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Opaque type and %checks type refinement functions do not refine the type Open

Typing: refinements

facebook/flow#6106 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
"property `prototype` is missing in statics of ..." Open

Typing: object model

facebook/flow#6110 · 2 comments · 9 reactions · 0 assignees · Indexed Sep 15, 2026
`instanceof Function` incorrectly refines to a callable Open

Typing: refinements

facebook/flow#6120 · 0 comments · 2 reactions · 0 assignees · Indexed Sep 15, 2026
[bug][v0.69.0] Loss of refinement after accessing object property Open

bug Typing: refinements

facebook/flow#6123 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
width subtyping with nonexact known properties fails in idiomatic javascript Open

Typing: object model

facebook/flow#6146 · 9 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Declare a global which may or may not be present Open

facebook/flow#6194 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Variables or 'generics' in literal types Open

feature request

facebook/flow#6226 · 0 comments · 2 reactions · 0 assignees · Indexed Sep 15, 2026
Flow "strict" mode is not applied to the module's index.js (v0.71.0) Open

facebook/flow#6232 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Flow does not recognize property exported using export * as X from 'a' Open

bug Typing: object model

facebook/flow#6234 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
How to ignore a specific lib? Open

question

facebook/flow#6256 · 4 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Method overloading fails to resolve to correct method Open

Typing: unions/intersections

facebook/flow#6265 · 1 comment · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Slow startup when using SyntheticEvent in flow-typed libdef Open

facebook/flow#6290 · 0 comments · 4 reactions · 0 assignees · Indexed Sep 15, 2026
Complex union type should work, but doesn't Open

facebook/flow#6291 · 3 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Command line option for excluding warnings Open

facebook/flow#6301 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Assert non primitive types in comparison expression Open

facebook/flow#6307 · 0 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Inconsistency when destructuring union types Open

destructuring Typing: unions/intersections

facebook/flow#6337 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Revocable Proxies are incorrectly Types Open

Accepting PRs Library definitions

facebook/flow#6387 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Opaque type subtyping with generics does not maintain exactness Open

Typing: opaque types

facebook/flow#6418 · 1 comment · 3 reactions · 0 assignees · Indexed Sep 15, 2026
Opaque type does not unify with underlying type in declaring module when used as type parameter Open

bug

facebook/flow#6421 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Feature request: option to suppress all "Cannot assign computed property using Symbol" errors Open

feature request

facebook/flow#6423 · 0 comments · 7 reactions · 0 assignees · Indexed Sep 15, 2026
Higher order generic function called on a generic function breaks generic inference Open

Typing: polymorphism

facebook/flow#6512 · 5 comments · 3 reactions · 0 assignees · Indexed Sep 15, 2026

facebook/flow

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