tools: require function declarations

.eslintrc.yaml

@@ -97,6 +97,7 @@ rules:
   eol-last: 2
   func-call-spacing: 2
   func-name-matching: 2
+  func-style: [2, declaration, {allowArrowFunctions: true}]
   indent: [2, 2, {ArrayExpression: first,
                   CallExpression: {arguments: first},
                   MemberExpression: 1,

doc/api/util.md

@@ -592,7 +592,7 @@ Returns `true` if the given `object` is a `Function`. Otherwise, returns
 const util = require('util');
 
 function Foo() {}
-const Bar = function() {};
+const Bar = () => {};
 
 util.isFunction({});
 // Returns: false

lib/_tls_legacy.js

@@ -448,9 +448,9 @@ CryptoStream.prototype.destroySoon = function(err) {
     // was written on this side was read from the other side.
     var self = this;
     var waiting = 1;
-    var finish = function() {
+    function finish() {
       if (--waiting === 0) self.destroy();
-    };
+    }
     this._opposite.once('end', finish);
     if (!this._finished) {
       this.once('finish', finish);

lib/crypto.js

@@ -645,11 +645,11 @@ function pbkdf2(password, salt, iterations, keylen, digest, callback) {
   // at this point, we need to handle encodings.
   var encoding = exports.DEFAULT_ENCODING;
   if (callback) {
-    var next = function(er, ret) {
+    function next(er, ret) {
       if (ret)
         ret = ret.toString(encoding);
       callback(er, ret);
-    };
+    }
     binding.PBKDF2(password, salt, iterations, keylen, digest, next);
   } else {
     var ret = binding.PBKDF2(password, salt, iterations, keylen, digest);

lib/internal/util.js

@@ -143,9 +143,9 @@ function cachedResult(fn) {
 //   B() instanceof A // true
 //   B() instanceof B // true
 function createClassWrapper(type) {
-  const fn = function(...args) {
+  function fn(...args) {
     return Reflect.construct(type, args, new.target || type);
-  };
+  }
   // Mask the wrapper function name and length values
   Object.defineProperties(fn, {
     name: {value: type.name},

test/addons-napi/test_async/test.js

@@ -6,8 +6,7 @@ const test_async = require(`./build/${common.buildType}/test_async`);
 test_async.Test(5, common.mustCall(function(err, val) {
   assert.strictEqual(err, null);
   assert.strictEqual(val, 10);
-  process.nextTick(common.mustCall(function() {}));
+  process.nextTick(common.mustCall());
 }));
 
-const cancelSuceeded = function() {};
-test_async.TestCancel(common.mustCall(cancelSuceeded));
+test_async.TestCancel(common.mustCall());

test/addons-napi/test_exception/test.js

@@ -4,12 +4,12 @@ const common = require('../../common');
 const test_exception = require(`./build/${common.buildType}/test_exception`);
 const assert = require('assert');
 const theError = new Error('Some error');
-const throwTheError = function() {
+function throwTheError() {
   throw theError;
-};
+}
 let caughtError;
 
-const throwNoError = function() {};
+const throwNoError = common.noop;
 
 // Test that the native side successfully captures the exception
 let returnedError = test_exception.returnException(throwTheError);

test/addons-napi/test_instanceof/test.js

@@ -57,14 +57,14 @@ if (typeof Symbol !== 'undefined' && 'hasInstance' in Symbol &&
       (theObject instanceof theConstructor));
   }
 
-  const MyClass = function MyClass() {};
+  function MyClass() {}
   Object.defineProperty(MyClass, Symbol.hasInstance, {
     value: function(candidate) {
       return 'mark' in candidate;
     }
   });
 
-  const MySubClass = function MySubClass() {};
+  function MySubClass() {}
   MySubClass.prototype = new MyClass();
 
   let x = new MySubClass();

test/addons/make-callback/test.js

@@ -57,9 +57,9 @@ const forward = vm.runInNewContext(`
     })
 `);
 // Runs in outer context.
-const endpoint = function($Object) {
+function endpoint($Object) {
   if (Object === $Object)
     throw new Error('bad');
   return Object;
-};
+}
 assert.strictEqual(Object, makeCallback(process, forward, endpoint));

test/inspector/inspector-helper.js

@@ -122,7 +122,7 @@ function timeout(message, multiplicator) {
                     TIMEOUT * (multiplicator || 1));
 }
 
-const TestSession = function(socket, harness) {
+function TestSession(socket, harness) {
   this.mainScriptPath = harness.mainScriptPath;
   this.mainScriptId = null;
 
@@ -147,7 +147,7 @@ const TestSession = function(socket, harness) {
         buffer = buffer.slice(consumed);
     } while (consumed);
   }).on('close', () => assert(this.expectClose_, 'Socket closed prematurely'));
-};
+}
 
 TestSession.prototype.scriptUrlForId = function(id) {
   return this.scripts_[id];
@@ -304,7 +304,7 @@ TestSession.prototype.testHttpResponse = function(path, check) {
 };
 
 
-const Harness = function(port, childProcess) {
+function Harness(port, childProcess) {
   this.port = port;
   this.mainScriptPath = mainScript;
   this.stderrFilters_ = [];
@@ -329,7 +329,7 @@ const Harness = function(port, childProcess) {
     this.returnCode_ = code;
     this.running_ = false;
   });
-};
+}
 
 Harness.prototype.addStderrFilter = function(regexp, callback) {
   this.stderrFilters_.push((message) => {

test/parallel/test-assert.js

@@ -449,7 +449,7 @@ a.throws(makeBlock(thrower, TypeError), function(err) {
 
     AnotherErrorType = class extends Error {};
 
-    const functionThatThrows = function() {
+    const functionThatThrows = () => {
       throw new AnotherErrorType('foo');
     };
 
@@ -493,6 +493,7 @@ a.throws(makeBlock(a.deepEqual, args, []));
 
 // more checking that arguments objects are handled correctly
 {
+  // eslint-disable-next-line func-style
   const returnArguments = function() { return arguments; };
 
   const someArgs = returnArguments('a');

test/parallel/test-child-process-fork-dgram.js

@@ -78,7 +78,7 @@ if (process.argv[2] === 'child') {
     });
   });
 
-  const sendMessages = function() {
+  function sendMessages() {
     const serverPort = parentServer.address().port;
 
     const timer = setInterval(function() {
@@ -102,7 +102,7 @@ if (process.argv[2] === 'child') {
         );
       }
     }, 1);
-  };
+  }
 
   parentServer.bind(0, '127.0.0.1');
 

test/parallel/test-child-process-fork-net.js

@@ -87,7 +87,7 @@ if (process.argv[2] === 'child') {
   }));
 
   // send net.Server to child and test by connecting
-  const testServer = function(callback) {
+  function testServer(callback) {
 
     // destroy server execute callback when done
     const progress = new ProgressTracker(2, function() {
@@ -116,7 +116,7 @@ if (process.argv[2] === 'child') {
     server.listen(0);
 
     // handle client messages
-    const messageHandlers = function(msg) {
+    function messageHandlers(msg) {
 
       if (msg.what === 'listening') {
         // make connections
@@ -138,13 +138,13 @@ if (process.argv[2] === 'child') {
         child.removeListener('message', messageHandlers);
         callback();
       }
-    };
+    }
 
     child.on('message', messageHandlers);
-  };
+  }
 
   // send net.Socket to child
-  const testSocket = function(callback) {
+  function testSocket(callback) {
 
     // create a new server and connect to it,
     // but the socket will be handled by the child
@@ -179,7 +179,7 @@ if (process.argv[2] === 'child') {
         server.close();
       });
     });
-  };
+  }
 
   // create server and send it to child
   let serverSuccess = false;

test/parallel/test-child-process-fork-net2.js

@@ -144,7 +144,7 @@ if (process.argv[2] === 'child') {
 
   server.listen(0, '127.0.0.1');
 
-  const closeServer = function() {
+  function closeServer() {
     server.close();
 
     setTimeout(function() {
@@ -153,7 +153,7 @@ if (process.argv[2] === 'child') {
       child2.send('close');
       child3.disconnect();
     }, 200);
-  };
+  }
 
   process.on('exit', function() {
     assert.strictEqual(disconnected, count);

test/parallel/test-child-process-spawn-typeerror.js

@@ -89,7 +89,7 @@ assert.throws(function() {
 // Argument types for combinatorics
 const a = [];
 const o = {};
-const c = function c() {};
+function c() {}
 const s = 'string';
 const u = undefined;
 const n = null;

test/parallel/test-cluster-disconnect.js

@@ -38,7 +38,7 @@ if (cluster.isWorker) {
   const servers = 2;
 
   // test a single TCP server
-  const testConnection = function(port, cb) {
+  const testConnection = (port, cb) => {
     const socket = net.connect(port, '127.0.0.1', () => {
       // buffer result
       let result = '';
@@ -52,7 +52,7 @@ if (cluster.isWorker) {
   };
 
   // test both servers created in the cluster
-  const testCluster = function(cb) {
+  const testCluster = (cb) => {
     let done = 0;
 
     for (let i = 0; i < servers; i++) {
@@ -67,7 +67,7 @@ if (cluster.isWorker) {
   };
 
   // start two workers and execute callback when both is listening
-  const startCluster = function(cb) {
+  const startCluster = (cb) => {
     const workers = 8;
     let online = 0;
 
@@ -81,7 +81,7 @@ if (cluster.isWorker) {
     }
   };
 
-  const test = function(again) {
+  const test = (again) => {
     //1. start cluster
     startCluster(common.mustCall(() => {
       //2. test cluster

test/parallel/test-cluster-master-error.js

@@ -101,7 +101,7 @@ if (cluster.isWorker) {
     // Check that the cluster died accidentally (non-zero exit code)
     masterExited = !!code;
 
-    const pollWorkers = function() {
+    const pollWorkers = () => {
       // When master is dead all workers should be dead too
       let alive = false;
       workers.forEach((pid) => alive = common.isAlive(pid));

test/parallel/test-cluster-master-kill.js

@@ -68,7 +68,7 @@ if (cluster.isWorker) {
     assert.strictEqual(code, 0);
 
     // check worker process status
-    const pollWorker = function() {
+    const pollWorker = () => {
       alive = common.isAlive(pid);
       if (alive) {
         setTimeout(pollWorker, 50);

test/parallel/test-cluster-message.js

@@ -80,7 +80,7 @@ if (cluster.isWorker) {
 
 
   let client;
-  const check = function(type, result) {
+  const check = (type, result) => {
     checks[type].receive = true;
     checks[type].correct = result;
     console.error('check', checks);

test/parallel/test-cluster-worker-exit.js

@@ -103,7 +103,7 @@ if (cluster.isWorker) {
     }
   }));
 
-  const finish_test = function() {
+  const finish_test = () => {
     try {
       checkResults(expected_results, results);
     } catch (exc) {

test/parallel/test-console-not-call-toString.js

@@ -23,7 +23,7 @@
 require('../common');
 const assert = require('assert');
 
-const func = function() {};
+function func() {}
 let toStringCalled = false;
 func.toString = function() {
   toStringCalled = true;

test/parallel/test-event-emitter-add-listeners.js

@@ -68,8 +68,8 @@ const EventEmitter = require('events');
 }
 
 {
-  const listen1 = function listen1() {};
-  const listen2 = function listen2() {};
+  const listen1 = () => {};
+  const listen2 = () => {};
   const ee = new EventEmitter();
 
   ee.once('newListener', function() {

test/parallel/test-event-emitter-once.js

@@ -33,9 +33,9 @@ e.emit('hello', 'a', 'b');
 e.emit('hello', 'a', 'b');
 e.emit('hello', 'a', 'b');
 
-const remove = function() {
+function remove() {
   assert.fail('once->foo should not be emitted');
-};
+}
 
 e.once('foo', remove);
 e.removeListener('foo', remove);

test/parallel/test-fs-access.js

@@ -7,10 +7,10 @@ const doesNotExist = path.join(common.tmpDir, '__this_should_not_exist');
 const readOnlyFile = path.join(common.tmpDir, 'read_only_file');
 const readWriteFile = path.join(common.tmpDir, 'read_write_file');
 
-const createFileWithPerms = function(file, mode) {
+function createFileWithPerms(file, mode) {
   fs.writeFileSync(file, '');
   fs.chmodSync(file, mode);
-};
+}
 
 common.refreshTmpDir();
 createFileWithPerms(readOnlyFile, 0o444);

test/parallel/test-fs-link.js

@@ -11,11 +11,11 @@ const srcPath = path.join(common.tmpDir, 'hardlink-target.txt');
 const dstPath = path.join(common.tmpDir, 'link1.js');
 fs.writeFileSync(srcPath, 'hello world');
 
-const callback = function(err) {
+function callback(err) {
   assert.ifError(err);
   const dstContent = fs.readFileSync(dstPath, 'utf8');
   assert.strictEqual('hello world', dstContent);
-};
+}
 
 fs.link(srcPath, dstPath, common.mustCall(callback));