Unnamed parameter with commander.js

Question

I am currently taking a look at commander.js as I want to implement a CLI using Node.js.

Using named parameters is easy, as the example of a "pizza" program shows:

program
  .version('0.0.1')
  .option('-p, --peppers', 'Add peppers')
  .option('-P, --pineapple', 'Add pineapple')
  .option('-b, --bbq', 'Add bbq sauce')
  .option('-c, --cheese [type]', 'Add the specified type of cheese [marble]', 'marble')
  .parse(process.argv);

Now, e.g., I can call the program using:

$ app -p -b

But what about an unnamed parameter? What if I want to call it using

$ app italian -p -b

? I think this is not so very uncommon, hence providing files for the cp command does not require you to use named parameters as well. It's just

$ cp source target

and not:

$ cp -s source -t target

How do I achieve this using commander.js?

And, how do I tell commander.js that unnamed parameters are required? E.g., if you take a look at the cp command, source and target are required.

Answer 1

With the present version of commander, it's possible to use positional arguments. See the docs on argument syntax for details, but using your cp example it would be something like:

program
.version('0.0.1')
.arguments('<source> <target>')
.action(function(source, target) {
    // do something with source and target
})
.parse(process.argv);

This program will complain if both arguments are not present, and give an appropriate warning message.

Answer 2

You get all the unnamed parameters through program.args. Add the following line to your example

console.log(' args: %j', program.args);

When you run your app with -p -b -c gouda arg1 arg2 you get

you ordered a pizza with:
- peppers
- bbq
- gouda cheese
args: ["arg1","arg2"]

Then you could write something like

copy args[0] to args[1] // just to give an idea