Use .demandOption in a Command Module

When using the Command Module pattern, is there a way to use the .demandOptions() method for each command, instead of in the invocation chain?

[sdcaulley]

@jly36963 Thank you for the example. That helps a lot.

[jly36963]

I don’t know if you can use positional and option in the command module object. I also don’t know if you can call demandOption at the command level, but you can on a per-option basis. In general, my opinion is that builder as function is more flexible and better documented than builder as object.

let input
input = 'arithmetic 3 5 --operation=add'
input = 'arithmetic 3 5'

yargs(input)
  .command({
    command: 'arithmetic <a> <b>',
    desc: 'arithmetic desc',
    builder: {
      a: { type: 'number', required: true },
      b: { type: 'number', required: true },
      operation: { 
        type: 'string', 
        choices: ['add', 'subtract', 'multiply', 'divide'],
        demandOption: 'Please provide an operation'
      }
    },
    // builder: yargs => yargs
    //   .positional('a', { type: 'number' })
    //   .positional('b', { type: 'number' })
    //   .option('operation', { 
    //     type: 'string', 
    //     choices: ['add', 'subtract', 'multiply', 'divide'] 
    //   })
    //   .demandOption('operation', 'Please provide an operation'),
    handler: argv => {
      const { a, b, operation } = argv
      let result, operator
      switch (operation) {
        case 'add':
          operator = '+'
          result = a + b
          break
        case 'subtract':
          operator = '-'
          result = a - b
          break
        default:
          console.log(`${operation} is not supported yet`)
          return
      }
      console.log(`${a} ${operator} ${b} = ${result}`)
    }
  })
  .strict()
  .parse()