Trying to use Optimist API help() to print usage()

Question

I'm new with optimist and I've done a bit of googling and try outs, but I still can't find an elegant way to add a --help option.

I see a help() option on the documentation. With this I would expect the following to work:

var argv = require('optimist')
  .usage('Some usage')
  .alias('l', 'local')
  .describe('l', 'uses local repo')
  .help()
  .argv

So on the shell if I typed ./myScript --help it would show the usage. I know that I can inspect the argvfor a -h or --help option and do console(argv.usage) to print the usage, but I was trying to use the API instead of hacking it.

Is this a valid question? Thanks for the help.

bitoiu

Answer 1

When you want to be able to display a usage, you want to keep a pointer to the object that is returned from the require(). This is because the object returned from the .argv is just a plain object, so there is no way to access the help() or showHelp() functions. Below is a contrived example that I think will point you in the right direction for what you're trying to do.

var optimist = require('optimist')
    .usage('$0: This is an example on how to use optimist')
    .describe('h', 'Display the usage')
    .describe('l', 'uses local repo')
    .alias('h', 'help')
    .alias('l', 'local');

var argv = optimist.argv;

if (argv.help) {
    optimist.showHelp();
    process.exit(0);
}

if (argv.local) {
    // Do stuff based on local repo
    console.info('Got the -l/--local flag!');
}

Then when you run the code, and pass in either -h or --help, you would get the following output:

node ./ex-optimist.js: This is an example on how to use optimist

Options:
  -h, --help   Display the usage
  -l, --local  uses local repo

Also note that using the .help function will return the usage as a string, and trying to use .argv after it will make your argv variable 'undefined'.