flow-bin

What is flow-bin?

The flow-bin npm package provides a command-line interface for Flow, a static type checker for JavaScript. Flow helps developers catch common errors early by adding type annotations to JavaScript code.

What are flow-bin's main functionalities?

Type Checking

Flow can be used to add type annotations to JavaScript functions and variables, which helps catch type errors during development.

/* @flow */
function add(a: number, b: number): number {
  return a + b;
}
add(1, 2); // No error
add('1', '2'); // Error: string is incompatible with number

Type Inference

Flow can infer types even if they are not explicitly annotated, providing type safety without requiring extensive type annotations.

/* @flow */
function square(n) {
  return n * n;
}
square(2); // No error
square('2'); // Error: string is incompatible with number

Type Definitions

Flow allows you to import and use type definitions from other files, making it easier to manage and reuse types across a project.

/* @flow */
import type { User } from './types';

function getUser(id: number): User {
  // Implementation
}

Other packages similar to flow-bin

typescript

TypeScript is a popular static type checker for JavaScript developed by Microsoft. It offers a superset of JavaScript with optional static types, and it has a large ecosystem and community support. Unlike Flow, TypeScript requires a compilation step to convert TypeScript code into JavaScript.

prop-types

PropTypes is a library for runtime type checking of React props. It is less comprehensive than Flow or TypeScript as it only checks types at runtime and is specifically designed for React components. It does not provide the same level of static analysis and type inference as Flow.

eslint-plugin-flowtype

ESLint plugin for Flow type annotations. It provides linting rules for Flow type annotations, helping to enforce consistent style and catch potential issues. It complements Flow by integrating type checking into the ESLint workflow.

README

flow-bin

Binary wrapper for Flow - A static type checker for JavaScript

macOS (x64), Linux (x64, arm64) and Windows (x64) binaries are currently provided.

CLI

For Yarn:

$ yarn add --dev flow-bin
$ yarn run flow --help

For npm, add { "scripts": { "flow": "flow" } } in package.json and run:

$ npm install --save-dev flow-bin
$ npm run flow --help

API

$ npm install --save flow-bin

const execFile = require('child_process').execFile;
const flow = require('flow-bin');

execFile(flow, ['check'], (err, stdout) => {
	console.log(stdout);
});

License

flow-bin is MIT-licensed.

Releases

New Release

1. make push VERSION=0.122.0 (use the same version as Flow)
2. Publish to npm: make publish (run npm adduser the first time to log in)

Inspect a Release Before Publishing

npm pack
tar xf "flow-bin-$(node -p 'require("./package.json").version').tgz"
cd package
npm run verify