@babel/plugin-syntax-flow

What is @babel/plugin-syntax-flow?

The @babel/plugin-syntax-flow npm package allows Babel to parse specific syntaxes provided by Flow, a static type checker for JavaScript. This plugin only enables Babel to recognize and parse Flow syntax; it does not apply any transformations. This is particularly useful for projects that want to benefit from type checking in development without including type annotations in the production code.

What are @babel/plugin-syntax-flow's main functionalities?

Type Annotations

Enables syntax for type annotations in function parameters and return types. This feature allows developers to specify the expected type of parameters and the return type of functions.

function square(n: number): number {
  return n * n;
}

Interface Declaration

Supports declaring interfaces, which can be used to specify the structure of objects. Interfaces in Flow help in defining contracts within your code.

interface Serializable {
  serialize(): string;
}

Type Aliases

Allows the creation of type aliases, which can be used to create custom types based on existing ones. This is useful for simplifying complex type definitions or creating more readable code.

type Point = {
  x: number,
  y: number
};

Other packages similar to @babel/plugin-syntax-flow

@babel/preset-flow

Similar to @babel/plugin-syntax-flow, but as a preset, it includes not only the syntax plugin but also plugins for transforming Flow annotations. This makes it a more comprehensive solution for projects using Flow.

flow-bin

While not a Babel plugin, flow-bin is the official Flow CLI that can be used for type checking Flow-typed JavaScript files. It serves a different purpose by providing the type checking itself, whereas @babel/plugin-syntax-flow only enables Babel to parse Flow syntax.

typescript

TypeScript is a superset of JavaScript that adds static types. It serves a similar purpose to Flow but is a different ecosystem. TypeScript has its own compiler and Babel can be configured to strip TypeScript types, similar to how @babel/plugin-syntax-flow works for Flow.

README

@babel/plugin-syntax-flow

Installation

npm install --save-dev @babel/plugin-syntax-flow

Usage

Via .babelrc (Recommended)

.babelrc

{
  "plugins": ["@babel/plugin-syntax-flow"]
}

Via CLI

babel --plugins @babel/plugin-syntax-flow script.js

Via Node API

require("@babel/core").transform("code", {
  plugins: ["@babel/plugin-syntax-flow"]
});