How do I pass command line arguments to a Node.js program?

manpreet Best Answer 3 years ago

I have a web server written in Node.js and I would like to launch with a specific folder. I'm not sure how to access arguments in JavaScript. I'm running node like this:

$ node server.js folder

here server.js is my server code. Node.js help says this is possible:

$ node -h
Usage: node [options] script.js [arguments]

How would I access those arguments in JavaScript? Somehow I was not able to find this information on the web.

manpreet 3 years ago

The arguments are stored in process.argv

process.argv is an array containing the command line arguments. The first element will be 'node', the second element will be the name of the JavaScript file. The next elements will be any additional command line arguments.

// print process.argv
process.argv.forEach(function (val, index, array) {
  console.log(index + ': ' + val);
});

This will generate:

$ node process-2.js one two=three four
0: node
1: /Users/mjr/work/node/process-2.js
2: one
3: two=three
4: four

manpreet 3 years ago

To normalize the arguments like a regular javascript function would receive, I do this in my node.js shell scripts:

var args = process.argv.slice(2);

Note that the first arg is usually the path to nodejs, and the second arg is the location of the script you're executing.

manpreet 3 years ago

const args = process.argv;
console.log(args);

This returns:

$ node server.js one two=three four
['node', '/home/server.js', 'one', 'two=three', 'four']