tools: lint for strict equality for non null checks

.eslintrc

@@ -50,6 +50,8 @@ rules:
   no-fallthrough: 2
   ## disallow declaring the same variable more than once
   no-redeclare: 2
+  ## enforce using strict comparison besides equal null checks
+  eqeqeq: [2, "allow-null"]
 
   # Stylistic Issues
   # list: https://github.com/eslint/eslint/tree/master/docs/rules#stylistic-issues

lib/_debugger.js

@@ -187,7 +187,7 @@ Client.prototype._addScript = function(desc) {
   this.scripts[desc.id] = desc;
   if (desc.name) {
     desc.isNative = (desc.name.replace('.js', '') in natives) ||
-                    desc.name == 'node.js';
+                    desc.name === 'node.js';
   }
 };
 
@@ -202,7 +202,7 @@ Client.prototype._onResponse = function(res) {
   var index = -1;
 
   this._reqCallbacks.some(function(fn, i) {
-    if (fn.request_seq == res.body.request_seq) {
+    if (fn.request_seq === res.body.request_seq) {
       cb = fn;
       index = i;
       return true;
@@ -212,25 +212,25 @@ Client.prototype._onResponse = function(res) {
   var self = this;
   var handled = false;
 
-  if (res.headers.Type == 'connect') {
+  if (res.headers.Type === 'connect') {
     // Request a list of scripts for our own storage.
     self.reqScripts();
     self.emit('ready');
     handled = true;
 
-  } else if (res.body && res.body.event == 'break') {
+  } else if (res.body && res.body.event === 'break') {
     this.emit('break', res.body);
     handled = true;
 
-  } else if (res.body && res.body.event == 'exception') {
+  } else if (res.body && res.body.event === 'exception') {
     this.emit('exception', res.body);
     handled = true;
 
-  } else if (res.body && res.body.event == 'afterCompile') {
+  } else if (res.body && res.body.event === 'afterCompile') {
     this._addHandle(res.body.body.script);
     handled = true;
 
-  } else if (res.body && res.body.event == 'scriptCollected') {
+  } else if (res.body && res.body.event === 'scriptCollected') {
     // ???
     this._removeScript(res.body.body.script);
     handled = true;
@@ -328,7 +328,7 @@ Client.prototype.reqScopes = function(cb) {
 Client.prototype.reqEval = function(expression, cb) {
   var self = this;
 
-  if (this.currentFrame == NO_FRAME) {
+  if (this.currentFrame === NO_FRAME) {
     // Only need to eval in global scope.
     this.reqFrameEval(expression, NO_FRAME, cb);
     return;
@@ -358,7 +358,7 @@ Client.prototype.reqEval = function(expression, cb) {
 
 // Finds the first scope in the array in which the expression evals.
 Client.prototype._reqFramesEval = function(expression, evalFrames, cb) {
-  if (evalFrames.length == 0) {
+  if (evalFrames.length === 0) {
     // Just eval in global scope.
     this.reqFrameEval(expression, NO_FRAME, cb);
     return;
@@ -382,7 +382,7 @@ Client.prototype.reqFrameEval = function(expression, frame, cb) {
     arguments: { expression: expression }
   };
 
-  if (frame == NO_FRAME) {
+  if (frame === NO_FRAME) {
     req.arguments.global = true;
   } else {
     req.arguments.frame = frame;
@@ -529,9 +529,9 @@ Client.prototype.mirrorObject = function(handle, depth, cb) {
       var mirror;
       var waiting = 1;
 
-      if (handle.className == 'Array') {
+      if (handle.className === 'Array') {
         mirror = [];
-      } else if (handle.className == 'Date') {
+      } else if (handle.className === 'Date') {
         mirror = new Date(handle.value);
       } else {
         mirror = {};
@@ -1103,7 +1103,7 @@ Interface.prototype.list = function(delta) {
     for (var i = 0; i < lines.length; i++) {
       var lineno = res.fromLine + i + 1;
       if (lineno < from || lineno > to) continue;
-
+      /* eslint-disable eqeqeq */
       const current = lineno == 1 + client.currentSourceLine;
       const breakpoint = client.breakpoints.some(function(bp) {
         return (bp.scriptReq === client.currentScript ||
@@ -1119,6 +1119,7 @@ Interface.prototype.list = function(delta) {
 
         client.currentSourceColumn -= wrapper.length;
       }
+      /* eslint-enable eqeqeq */
 
       // Highlight executing statement
       var line;
@@ -1158,7 +1159,7 @@ Interface.prototype.backtrace = function() {
       return;
     }
 
-    if (bt.totalFrames == 0) {
+    if (bt.totalFrames === 0) {
       self.print('(empty stack)');
     } else {
       const trace = [];
@@ -1200,10 +1201,10 @@ Interface.prototype.scripts = function() {
     var script = client.scripts[id];
     if (script !== null && typeof script === 'object' && script.name) {
       if (displayNatives ||
-          script.name == client.currentScript ||
+          script.name === client.currentScript ||
           !script.isNative) {
         scripts.push(
-            (script.name == client.currentScript ? '* ' : '  ') +
+            (script.name === client.currentScript ? '* ' : '  ') +
             id + ': ' +
             path.basename(script.name)
         );
@@ -1363,7 +1364,9 @@ Interface.prototype.setBreakpoint = function(script, line,
     };
   } else {
     // setBreakpoint('scriptname')
-    if (script != +script && !this.client.scripts[script]) {
+    if (script != +script && // eslint-disable-line eqeqeq
+      !this.client.scripts[script]
+    ) {
       var scripts = this.client.scripts;
       for (var id in scripts) {
         if (scripts[id] &&

lib/_http_incoming.js

@@ -27,8 +27,8 @@ function IncomingMessage(socket) {
   this.socket = socket;
   this.connection = socket;
 
-  this.httpVersionMajor = null;
-  this.httpVersionMinor = null;
+  this.httpVersionMajor = 0;
+  this.httpVersionMinor = 0;
   this.httpVersion = null;
   this.complete = false;
   this.headers = {};

lib/_http_server.js

@@ -516,7 +516,7 @@ function connectionListener(socket) {
     }
 
     if (req.headers.expect !== undefined &&
-        (req.httpVersionMajor == 1 && req.httpVersionMinor == 1)) {
+        (req.httpVersionMajor === 1 && req.httpVersionMinor === 1)) {
       if (continueExpression.test(req.headers.expect)) {
         res._expect_continue = true;
 

lib/_stream_transform.js

@@ -183,7 +183,7 @@ function done(stream, er) {
   var ts = stream._transformState;
 
   if (ws.length)
-    throw new Error('Calling transform done when ws.length != 0');
+    throw new Error('Calling transform done when ws.length !== 0');
 
   if (ts.transforming)
     throw new Error('Calling transform done when still transforming');

lib/_tls_wrap.js

@@ -523,7 +523,7 @@ TLSSocket.prototype.renegotiate = function(options, callback) {
 };
 
 TLSSocket.prototype.setMaxSendFragment = function setMaxSendFragment(size) {
-  return this._handle.setMaxSendFragment(size) == 1;
+  return this._handle.setMaxSendFragment(size) === 1;
 };
 
 TLSSocket.prototype.getTLSTicket = function getTLSTicket() {

lib/assert.js

@@ -23,6 +23,7 @@
 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 'use strict';
+/* eslint-disable eqeqeq */
 
 // UTILITY
 const compare = process.binding('buffer').compare;
@@ -164,7 +165,7 @@ function _deepEqual(actual, expected, strict) {
            actual.lastIndex === expected.lastIndex &&
            actual.ignoreCase === expected.ignoreCase;
 
-  // 7.4. Other pairs that do not both pass typeof value == 'object',
+  // 7.4. Other pairs that do not both pass typeof value === 'object',
   // equivalence is determined by ==.
   } else if ((actual === null || typeof actual !== 'object') &&
              (expected === null || typeof expected !== 'object')) {
@@ -187,7 +188,7 @@ function _deepEqual(actual, expected, strict) {
 }
 
 function isArguments(object) {
-  return Object.prototype.toString.call(object) == '[object Arguments]';
+  return Object.prototype.toString.call(object) === '[object Arguments]';
 }
 
 function objEquiv(a, b, strict) {
@@ -271,7 +272,7 @@ function expectedException(actual, expected) {
     return false;
   }
 
-  if (Object.prototype.toString.call(expected) == '[object RegExp]') {
+  if (Object.prototype.toString.call(expected) === '[object RegExp]') {
     return expected.test(actual);
   }
 

lib/buffer.js

@@ -72,7 +72,7 @@ Object.setPrototypeOf(Buffer, Uint8Array);
 
 
 function SlowBuffer(length) {
-  if (+length != length)
+  if (+length != length) // eslint-disable-line eqeqeq
     length = 0;
   if (length > 0)
     flags[kNoZeroFill] = 1;

lib/dgram.js

@@ -39,21 +39,21 @@ function lookup6(address, callback) {
 
 
 function newHandle(type) {
-  if (type == 'udp4') {
+  if (type === 'udp4') {
     const handle = new UDP();
     handle.lookup = lookup4;
     return handle;
   }
 
-  if (type == 'udp6') {
+  if (type === 'udp6') {
     const handle = new UDP();
     handle.lookup = lookup6;
     handle.bind = handle.bind6;
     handle.send = handle.send6;
     return handle;
   }
 
-  if (type == 'unix_dgram')
+  if (type === 'unix_dgram')
     throw new Error('"unix_dgram" type sockets are not supported any more');
 
   throw new Error('Bad socket type specified. Valid types are: udp4, udp6');
@@ -140,7 +140,7 @@ Socket.prototype.bind = function(port_ /*, address, callback*/) {
 
   self._healthCheck();
 
-  if (this._bindState != BIND_STATE_UNBOUND)
+  if (this._bindState !== BIND_STATE_UNBOUND)
     throw new Error('Socket is already bound');
 
   this._bindState = BIND_STATE_BINDING;
@@ -326,12 +326,12 @@ Socket.prototype.send = function(buffer,
 
   self._healthCheck();
 
-  if (self._bindState == BIND_STATE_UNBOUND)
+  if (self._bindState === BIND_STATE_UNBOUND)
     self.bind({port: 0, exclusive: true}, null);
 
   // If the socket hasn't been bound yet, push the outbound packet onto the
   // send queue and send after binding is complete.
-  if (self._bindState != BIND_STATE_BOUND) {
+  if (self._bindState !== BIND_STATE_BOUND) {
     enqueue(self, [buffer, port, address, callback]);
     return;
   }

lib/fs.js

@@ -1113,9 +1113,11 @@ fs.chownSync = function(path, uid, gid) {
 
 // converts Date or number to a fractional UNIX timestamp
 function toUnixTimestamp(time) {
+  /* eslint-disable eqeqeq */
   if (typeof time === 'string' && +time == time) {
     return +time;
   }
+  /* eslint-enable eqeqeq */
   if (typeof time === 'number') {
     if (!Number.isFinite(time) || time < 0) {
       return Date.now() / 1000;

lib/internal/child_process.js

@@ -823,7 +823,7 @@ function getSocketList(type, slave, key) {
 function maybeClose(subprocess) {
   subprocess._closesGot++;
 
-  if (subprocess._closesGot == subprocess._closesNeeded) {
+  if (subprocess._closesGot === subprocess._closesNeeded) {
     subprocess.emit('close', subprocess.exitCode, subprocess.signalCode);
   }
 }

lib/internal/linkedlist.js

@@ -9,7 +9,7 @@ exports.init = init;
 
 // show the most idle item
 function peek(list) {
-  if (list._idlePrev == list) return null;
+  if (list._idlePrev === list) return null;
   return list._idlePrev;
 }
 exports.peek = peek;

lib/internal/v8_prof_polyfill.js

@@ -34,7 +34,7 @@ const os = {
       // Filter out vdso and vsyscall entries.
       const arg = args[args.length - 1];
       if (arg === '[vdso]' ||
-          arg == '[vsyscall]' ||
+          arg === '[vsyscall]' ||
           /^[0-9a-f]+-[0-9a-f]+$/.test(arg)) {
         return '';
       }

lib/net.js

@@ -129,7 +129,7 @@ function Socket(options) {
   } else if (options.fd !== undefined) {
     this._handle = createHandle(options.fd);
     this._handle.open(options.fd);
-    if ((options.fd == 1 || options.fd == 2) &&
+    if ((options.fd === 1 || options.fd === 2) &&
         (this._handle instanceof Pipe) &&
         process.platform === 'win32') {
       // Make stdout and stderr blocking on Windows
@@ -503,7 +503,7 @@ Socket.prototype.destroy = function(exception) {
 function onread(nread, buffer) {
   var handle = this;
   var self = handle.owner;
-  assert(handle === self._handle, 'handle != self._handle');
+  assert(handle === self._handle, 'handle !== self._handle');
 
   self._unrefTimer();
 
@@ -678,7 +678,7 @@ Socket.prototype._writeGeneric = function(writev, data, encoding, cb) {
 
   // If it was entirely flushed, we can write some more right now.
   // However, if more is left in the queue, then wait until that clears.
-  if (req.async && this._handle.writeQueueSize != 0)
+  if (req.async && this._handle.writeQueueSize !== 0)
     req.cb = cb;
   else
     cb();
@@ -1034,7 +1034,7 @@ function afterConnect(status, handle, req, readable, writable) {
   self._connecting = false;
   self._sockname = null;
 
-  if (status == 0) {
+  if (status === 0) {
     self.readable = readable;
     self.writable = writable;
     self._unrefTimer();

lib/punycode.js

@@ -2,11 +2,11 @@
 ;(function(root) {
 
 	/** Detect free variables */
-	var freeExports = typeof exports == 'object' && exports &&
+	var freeExports = typeof exports === 'object' && exports &&
 		!exports.nodeType && exports;
-	var freeModule = typeof module == 'object' && module &&
+	var freeModule = typeof module === 'object' && module &&
 		!module.nodeType && module;
-	var freeGlobal = typeof global == 'object' && global;
+	var freeGlobal = typeof global === 'object' && global;
 	if (
 		freeGlobal.global === freeGlobal ||
 		freeGlobal.window === freeGlobal ||
@@ -206,7 +206,7 @@
 	function digitToBasic(digit, flag) {
 		//  0..25 map to ASCII a..z or A..Z
 		// 26..35 map to ASCII 0..9
-		return digit + 22 + 75 * (digit < 26) - ((flag != 0) << 5);
+		return digit + 22 + 75 * (digit < 26) - ((flag !== 0) << 5);
 	}
 
 	/**
@@ -508,8 +508,8 @@
 	// Some AMD build optimizers, like r.js, check for specific condition patterns
 	// like the following:
 	if (
-		typeof define == 'function' &&
-		typeof define.amd == 'object' &&
+		typeof define === 'function' &&
+		typeof define.amd === 'object' &&
 		define.amd
 	) {
 		define('punycode', function() {