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.
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!');
}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 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 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.
Check if
argvhas a specific flag
$ npm install has-flag
// 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
Returns a boolean for whether the flag exists.
It correctly stops looking after an -- argument terminator.
Type: string
CLI flag to look for. The -- prefix is optional.
Type: string[]
Default: process.argv
CLI arguments.
FAQs
Check if argv has a specific flag
The npm package has-flag receives a total of 176,690,796 weekly downloads. As such, has-flag popularity was classified as popular.
We found that has-flag demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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