tty: refactor to es6

PR-URL: nodejs#17615
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

lib/tty.js

@@ -21,11 +21,9 @@
 
 'use strict';
 
-const util = require('util');
+const { inherits, _errnoException, _extend } = require('util');
 const net = require('net');
 const { TTY, isTTY } = process.binding('tty_wrap');
-const { inherits } = util;
-const errnoException = util._errnoException;
 const errors = require('internal/errors');
 const readline = require('readline');
 const { release } = require('os');
@@ -41,7 +39,6 @@ function isatty(fd) {
   return Number.isInteger(fd) && fd >= 0 && isTTY(fd);
 }
 
-
 function ReadStream(fd, options) {
   if (!(this instanceof ReadStream))
     return new ReadStream(fd, options);
@@ -54,7 +51,7 @@ function ReadStream(fd, options) {
     throw new errors.SystemError(ctx);
   }
 
-  options = util._extend({
+  options = _extend({
     highWaterMark: 0,
     readable: true,
     writable: false,
@@ -74,7 +71,6 @@ ReadStream.prototype.setRawMode = function(flag) {
   this.isRaw = flag;
 };
 
-
 function WriteStream(fd) {
   if (!(this instanceof WriteStream))
     return new WriteStream(fd);
@@ -100,16 +96,15 @@ function WriteStream(fd) {
   // Ref: https://github.com/nodejs/node/pull/1771#issuecomment-119351671
   this._handle.setBlocking(true);
 
-  var winSize = new Array(2);
-  var err = this._handle.getWindowSize(winSize);
+  const winSize = new Array(2);
+  const err = this._handle.getWindowSize(winSize);
   if (!err) {
     this.columns = winSize[0];
     this.rows = winSize[1];
   }
 }
 inherits(WriteStream, net.Socket);
 
-
 WriteStream.prototype.isTTY = true;
 
 WriteStream.prototype.getColorDepth = function(env = process.env) {
@@ -178,25 +173,23 @@ WriteStream.prototype.getColorDepth = function(env = process.env) {
 };
 
 WriteStream.prototype._refreshSize = function() {
-  var oldCols = this.columns;
-  var oldRows = this.rows;
-  var winSize = new Array(2);
-  var err = this._handle.getWindowSize(winSize);
+  const oldCols = this.columns;
+  const oldRows = this.rows;
+  const winSize = new Array(2);
+  const err = this._handle.getWindowSize(winSize);
   if (err) {
-    this.emit('error', errnoException(err, 'getWindowSize'));
+    this.emit('error', _errnoException(err, 'getWindowSize'));
     return;
   }
-  var newCols = winSize[0];
-  var newRows = winSize[1];
+  const [newCols, newRows] = winSize;
   if (oldCols !== newCols || oldRows !== newRows) {
     this.columns = newCols;
     this.rows = newRows;
     this.emit('resize');
   }
 };
 
-
-// backwards-compat
+// Backwards-compat
 WriteStream.prototype.cursorTo = function(x, y) {
   readline.cursorTo(this, x, y);
 };
@@ -213,5 +206,4 @@ WriteStream.prototype.getWindowSize = function() {
   return [this.columns, this.rows];
 };
 
-
 module.exports = { isatty, ReadStream, WriteStream };