child_process: minor cleanup of internals

This commit removes self = this style assignments and replaces
some array iteration functions with a simpler for loop.

PR-URL: #12348
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

lib/internal/child_process.js

@@ -157,8 +157,6 @@ const handleConversion = {
 function ChildProcess() {
   EventEmitter.call(this);
 
-  var self = this;
-
   this._closesNeeded = 1;
   this._closesGot = 0;
   this.connected = false;
@@ -171,41 +169,31 @@ function ChildProcess() {
   this._handle = new Process();
   this._handle.owner = this;
 
-  this._handle.onexit = function(exitCode, signalCode) {
-    //
-    // follow 0.4.x behaviour:
-    //
-    // - normally terminated processes don't touch this.signalCode
-    // - signaled processes don't touch this.exitCode
-    //
-    // new in 0.9.x:
-    //
-    // - spawn failures are reported with exitCode < 0
-    //
-    var syscall = self.spawnfile ? 'spawn ' + self.spawnfile : 'spawn';
-    var err = (exitCode < 0) ? errnoException(exitCode, syscall) : null;
-
+  this._handle.onexit = (exitCode, signalCode) => {
     if (signalCode) {
-      self.signalCode = signalCode;
+      this.signalCode = signalCode;
     } else {
-      self.exitCode = exitCode;
+      this.exitCode = exitCode;
     }
 
-    if (self.stdin) {
-      self.stdin.destroy();
+    if (this.stdin) {
+      this.stdin.destroy();
     }
 
-    self._handle.close();
-    self._handle = null;
+    this._handle.close();
+    this._handle = null;
 
     if (exitCode < 0) {
-      if (self.spawnfile)
-        err.path = self.spawnfile;
+      var syscall = this.spawnfile ? 'spawn ' + this.spawnfile : 'spawn';
+      const err = errnoException(exitCode, syscall);
+
+      if (this.spawnfile)
+        err.path = this.spawnfile;
 
-      err.spawnargs = self.spawnargs.slice(1);
-      self.emit('error', err);
+      err.spawnargs = this.spawnargs.slice(1);
+      this.emit('error', err);
     } else {
-      self.emit('exit', self.exitCode, self.signalCode);
+      this.emit('exit', this.exitCode, this.signalCode);
     }
 
     // if any of the stdio streams have not been touched,
@@ -214,9 +202,9 @@ function ChildProcess() {
     // Do it on nextTick so that the user has one last chance
     // to consume the output, if for example they only want to
     // start reading the data once the process exits.
-    process.nextTick(flushStdio, self);
+    process.nextTick(flushStdio, this);
 
-    maybeClose(self);
+    maybeClose(this);
   };
 }
 util.inherits(ChildProcess, EventEmitter);
@@ -262,10 +250,10 @@ function getHandleWrapType(stream) {
 
 
 ChildProcess.prototype.spawn = function(options) {
-  const self = this;
   var ipc;
   var ipcFd;
   var i;
+
   // If no `stdio` option was given - use default
   var stdio = options.stdio || 'pipe';
 
@@ -291,7 +279,7 @@ ChildProcess.prototype.spawn = function(options) {
       err === uv.UV_EMFILE ||
       err === uv.UV_ENFILE ||
       err === uv.UV_ENOENT) {
-    process.nextTick(onErrorNT, self, err);
+    process.nextTick(onErrorNT, this, err);
     // There is no point in continuing when we've hit EMFILE or ENFILE
     // because we won't be able to set up the stdio file descriptors.
     // It's kind of silly that the de facto spec for ENOENT (the test suite)
@@ -319,20 +307,20 @@ ChildProcess.prototype.spawn = function(options) {
     if (stream.type === 'ignore') continue;
 
     if (stream.ipc) {
-      self._closesNeeded++;
+      this._closesNeeded++;
       continue;
     }
 
     if (stream.handle) {
       // when i === 0 - we're dealing with stdin
       // (which is the only one writable pipe)
-      stream.socket = createSocket(self.pid !== 0 ?
+      stream.socket = createSocket(this.pid !== 0 ?
           stream.handle : null, i > 0);
 
-      if (i > 0 && self.pid !== 0) {
-        self._closesNeeded++;
-        stream.socket.on('close', function() {
-          maybeClose(self);
+      if (i > 0 && this.pid !== 0) {
+        this._closesNeeded++;
+        stream.socket.on('close', () => {
+          maybeClose(this);
         });
       }
     }
@@ -345,9 +333,10 @@ ChildProcess.prototype.spawn = function(options) {
   this.stderr = stdio.length >= 3 && stdio[2].socket !== undefined ?
       stdio[2].socket : null;
 
-  this.stdio = stdio.map(function(stdio) {
-    return stdio.socket === undefined ? null : stdio.socket;
-  });
+  this.stdio = [];
+
+  for (i = 0; i < stdio.length; i++)
+    this.stdio.push(stdio[i].socket === undefined ? null : stdio[i].socket);
 
   // Add .send() method and start listening for IPC data
   if (ipc !== undefined) setupChannel(this, ipc);
@@ -778,12 +767,10 @@ function _validateStdio(stdio, sync) {
   // (i.e. PipeWraps or fds)
   stdio = stdio.reduce(function(acc, stdio, i) {
     function cleanup() {
-      acc.filter(function(stdio) {
-        return stdio.type === 'pipe' || stdio.type === 'ipc';
-      }).forEach(function(stdio) {
-        if (stdio.handle)
-          stdio.handle.close();
-      });
+      for (var i = 0; i < acc.length; i++) {
+        if ((acc[i].type === 'pipe' || acc[i].type === 'ipc') && acc[i].handle)
+          acc[i].handle.close();
+      }
     }
 
     // Defaults
@@ -860,7 +847,7 @@ function _validateStdio(stdio, sync) {
     return acc;
   }, []);
 
-  return {stdio: stdio, ipc: ipc, ipcFd: ipcFd};
+  return { stdio, ipc, ipcFd };
 }