http: use arrow function to take advantage of lexical `this`?

[originalfoo]

• Version: 6.2.1
• Platform:
• Subsystem: lib/_http_outgoing.js

In OutgoingMessage.prototype.end there's a self var that's only used once for the finish() function - would it be better to use an arrow function instead?

Current code: https://github.com/nodejs/node/blob/master/lib/_http_outgoing.js#L549

  var self = this;
  function finish() {
    self.emit('finish');
  }

Proposed change:

let finish = () => this.emit('finish'); // lexical `this`

Also, as the finish() function isn't used until the code around L584, would it be worth moving the function closer to where it's used (along with the callback check) to aid code clarity?

// keep these 3 blocks together as they are related

let finish = () => this.emit('finish');

if (typeof callback === 'function')
  this.once('finish', callback);

if (this._hasBody && this.chunkedEncoding) {
  ret = this._send('0\r\n' + this._trailer + '\r\n', 'latin1', finish);
} else {
  // Force a flush, HACK.
  ret = this._send('', 'latin1', finish);
}

[Fishrock123]

We'd be happy to review a pull request if you'd like to make one. :)

[originalfoo]

Will do 👍

[originalfoo]

PR sent :)