has-flag

What is has-flag?

The has-flag npm package is a simple utility that checks if a specific flag is provided in the command line arguments (process.argv). It is commonly used to determine if a flag is set when running a Node.js script from the terminal.

What are has-flag's main functionalities?

Check for the presence of a command line flag

This feature allows you to check if a flag, such as '--unicorn', is passed to the script. The code sample demonstrates how to use has-flag to check for the 'unicorn' flag and log a message if it is present.

const hasFlag = require('has-flag');

if (hasFlag('unicorn')) {
    console.log('We have a unicorn!');
}

Other packages similar to has-flag

minimist

Minimist is a more comprehensive command line argument parsing library. Unlike has-flag, which only checks for the existence of flags, minimist parses all arguments into a structured object, making it easier to work with multiple types of command line parameters.

commander

Commander is a complete solution for building command line applications in Node.js. It provides a high-level API for parsing command line options, as well as a variety of other features such as subcommands and automated help generation. Commander is more feature-rich compared to has-flag, which is focused solely on flag detection.

yargs

Yargs is another full-featured command line option parser that offers advanced features like command chaining, argument validation, and automatic help generation. It is more complex and feature-complete than has-flag, which is a minimalistic tool for flag checking.

README

has-flag

Check if argv has a specific flag

Install

$ npm install has-flag

Usage

// foo.js
import hasFlag from 'has-flag';

hasFlag('unicorn');
//=> true

hasFlag('--unicorn');
//=> true

hasFlag('f');
//=> true

hasFlag('-f');
//=> true

hasFlag('foo=bar');
//=> true

hasFlag('foo');
//=> false

hasFlag('rainbow');
//=> false

$ node foo.js -f --unicorn --foo=bar -- --rainbow

API

hasFlag(flag, argv?)

Returns a boolean for whether the flag exists.

It correctly stops looking after an -- argument terminator.

flag

Type: string

CLI flag to look for. The -- prefix is optional.

argv

Type: string[]
Default: process.argv

CLI arguments.

Get professional support for this package with a Tidelift subscription
_{Tidelift helps make open source sustainable for maintainers while giving companies
assurances about security, maintenance, and licensing for their dependencies.}