[class] remove this instanceof itself checks

[jimmywarting]

const util = require('util');
const EventEmitter = require('events');

function MyStream() {
  if (!(this instanceof MyStream)) {
    return new MyStream();
  }
  
  EventEmitter.call(this);
}

util.inherits(MyStream, EventEmitter);

MyStream.prototype.write = function(data) {
  this.emit('data', data);
};

const stream = new MyStream();

Is transformed to

const util = require('util');
const EventEmitter = require('events');

class MyStream extends EventEmitter {
  constructor() {
    if (!(this instanceof MyStream)) {
      return new MyStream();
    }

    super();
  }

  write(data) {
    this.emit('data', data);
  }
}

const stream = new MyStream();

The problem with it are

• this is used before calling super()
• this instanceof MyStream will always be true (cuz you can never invoke MyStream without the new keyword)
  • I think the if check should be removed altogether. Leaving it with just the super() left

[uniibu]

There are a lot of other bugs for the class transform, and like nene said, it should be rewritten rather than adding fixes over fixes.

On the side note, Classes can be invoked using its static methods returning a new instance of the class, hence no new is needed.

[nene]

@jimmywarting The first bug relating to super() is already known: #186

Regarding this instanceof check. When some code relies on this, then converting this function to class was really a mistake. So instead of removing this check I'm leaning towards detecting it and preventing the class transform from happening in the first place.

[pitust]

Or transfarming the caller to use the new operator