Flag arguments, boo! pt 1

index.js

// I think boolean arguments maybe kind of suck. I'm still making up my mind on this,
// but let me show you why I'm leaning the way I am.

// I have a function that fills out a form and optionally submits it.
// Maybe this is a function you'd use in a test suite or something similar.
function fillOutForm(values, submit = true) {
  // Do some stuff with the values

  if (submit) {
    form.submit()
  }
}

// Now let's use it.
fillOutForm({ name: 'Kyle', email: '[email protected]' })
fillOutForm({ name: 'Anna', email: '[email protected]' }, false)

// The problem with the boolean flag is that it conveys no information at the call site.
// If this is an imported function and I see an argument that is only optionally added,
// I have to go all the way to the function definition (or docs) to figure out what it means.
// Sure, we do that all the time, but maybe it's a bit better to do something more verbose like this

const defaultOptions = {
  submit: true
}

function fillOutForm(values, options = defaultOptions) {
  // Do some stuff with the values

  const { submit } = options
  
  if (submit) {
    form.submit()
  }
}

// Now the call sites give us a bit more information when we deny submission
fillOutForm({ name: 'Kyle', email: '[email protected]' })
fillOutForm({ name: 'Anna', email: '[email protected]' }, { submit: false })

// What do you think?