Flow

Getting Started

Never used a type system before or just new to Flow? Let's get you up and running in a few minutes.
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Type Annotations

Learn how to add Flow type annotations to your code: Primitives, Objects, Functions, Classes, and more.
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Type System

Learn how the type system in Flow works: Subtyping, Variance, Refinements, and more.
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CLI Commands

How to use Flow from the command line. Including how to manage the Flow background process.
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Configuration

Flow tries to work out of the box as much as possible, but can be configured to work with any codebase.
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Library Definitions

Learn how to create and use library definitions for the third-party code your code depends on.
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React

Learn how to use Flow to effectively type common and advanced React patterns.
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Tools

Detailed guides, tips, and resources on how to integrate Flow with different JavaScript tools.
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Editors

Detailed guides, tips, and resources on how to integrate Flow with different code editors.
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Linting

Learn how to configure Flow's linter to find potentially harmful code.
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Flow Strict

Learn how to enable stricter type checking on a file-by-file basis.
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