Support optional chaining operator

Great job here.

I want to suggest adding support for the optional chaining operator e.g

Code:

'use strict';

function greet(name) {
  name = name  || 'World'
  var isJohn = name && name.includes && name.includes('John')
  alert(isJohn ? 'Hello Admin' : 'Hello ' + name)
}

Current Output:

function greet(name = 'World') {
  const isJohn = name && name.includes && name.includes('John')
  alert(isJohn ? 'Hello Admin' : `Hello ${name}`)
}

Expected Output:

function greet(name = 'World') {
  const isJohn = name?.includes('John')
  alert(isJohn ? 'Hi Admin' : `Hello ${name}`)
}

[uniibu]

@frank-dspeed thanks for clarifying, although I never said that a stage 3 proposals have a chance to not be implemented. In fact, I don’t think there has ever been a stage 3 proposal that was eventually withdrawn/rejected. You are also correct that browsers indeed are implementing most of the stage 3 proposals, however, Lebab does not rely on browsers as its parser. It uses Espree and during the time i wrote that comment, optional chaining was still not implemented.

Going back, I would say this is now possible to do since Espree have already implemented it on their latest release v7.2.0 which includes PR #446 and was only released 6 days ago.

[DiegoRBaquero]

Optional chaining works in Node 14+, would be a great addition to lebab