Node Arguments Lab


  1. Implement a CLI app which generates random passwords
  2. Use two CLI arguments as the input of the app: one for length of the password and another for the number of randomly generated passwords.


You've been hired to enhance security at a major US bank amidst the breach in their database. As a security expert you know that offering users randomly generated passwords will make it hard for pesky hackers to brute force the attack. This app must use this command-line interface and be flexible to be used for passwords of different length and for various numbers of passwords.

In this lab, you will pass and access command-line arguments to implement a CLI app which generates random passwords.

Knowing how to pass and access command-line arguments is important in building CLI tools or small programs like the program which gives a random number.


  1. Implement a Node script password.js which takes 2 CLI arguments and prints random passwords based on the arguments.
  2. Use two arguments: length (first) and a number of passwords (second) to print, so that node password 2 2 and node password 10 3 are valid commands. The former will print 2 passwords with the length of 2 and the latter 3 passwords with the length of 10.
  3. Optional: implement generatePassword() function in the password.js to get random passwords. The name of the function doesn't matter. You don't even have to have a separate function, you can just implement the code in the file without a function. If it's too hard, look up the implementation online. The password generation is not the focus of this lab, so we won't test your passwords on strength or randomness. Just do your best not to hard code them. ;)
  4. Optional: Output error messages when the type of CLI arguments is wrong or when there's only 1 argument instead of 2.
  5. Finish program with process.exit(0)
  6. Run npm test to test

Extra Info

In the tests, you'll see child_process. It's a super easy core module which allows you to start any other programs/processes from within your Node app. We use it in the tests to verify that your app is actually taking in the CLI argument and not using some hard-coded values. To use child_proccess, all you do is pass parameters to its spawn() method:

process = childProcess.spawn(command, [scriptName, cliArgument1, cliArgument2])

Node's child_process.spawn is similar to how you run multiple processes with Ruby with Process.spawn.

In this lab, we are using child_process.spawn to start your password.js script with arguments 140 and 1. The 140 is the length of the password and the 1 is the number of password we need. The snippet goes like this:

passwordAppProcess = cp.spawn('node', ['password', '140', '1'])
passwordAppProcess.stdout.on('data', (data) => {
  // data is the output of the password.js  script

kill() is the command to terminate the child process (your password.js program).

View node-arguments-lab on and start learning to code for free.

View Node Arguments Lab on and start learning to code for free.

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