Flow - Am I Your Type?
summary
Flow is Facebook’s open source static type checker for JavaScript that supports gradual typing, type inference, and integrates with Babel, ESLint, editors, and webpack. It catches errors without annotations by tracing value flow and starts a persistent flow server that spawns parallel workers (about ten on a multicore laptop). Workflow tools include flow suggest, flow remove-types / node with flow-node, and flow-typed (about 570 third‑party defs compared to TypeScript’s ~2000). Strict null checking is default (strict null checking by default), and $FlowFixMe is an escape hatch.
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chapters (29)
- 0:00Intro
- 1:14Outline
- 1:48Static vs. Dynamic
- 2:11Why Use Types?
- 4:01Why Avoid Types?
- 4:38When to Use Types
- 5:04Flow Overview
- 6:31TypeScript Overview
- 10:14Installing Flow
- 10:53Running Flow
- 12:09Type Suggestions
- 13:04The Executing Code With Types ...
- 14:43Flow Analysis Example
- 15:42Uninitialized References
- 17:23Flow Types
- 18:56Maybe Type
- 21:47Basic Types Example
- 22:39Builtin Types
- 25:19Functions
- 27:34Arrays
- 30:54Classes
- 34:10Type Discrimination
- 35:11Unions For Enums
- 35:44Sharing Type Aliases Example
- 36:19Escape Hatch
- 36:53Flow Server ...
- 37:53Flow Project Checklist
- 39:30Summary
- 40:15Reasons to Prefer Flow Over TS
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