ES6-ify codebase

.eslintrc

@@ -9,6 +9,7 @@
     "ecmaVersion": 8,
     "sourceType": "module"
   },
+  "extends": "eslint:recommended",
   "rules": {
     "eqeqeq": 0,
     "guard-for-in": 2,
@@ -19,6 +20,7 @@
         "SwitchCase": 1
       }
     ],
+    "no-console": 0,
     "no-caller": 2,
     "no-undef": 2,
     "no-unused-vars": 2,
@@ -28,10 +30,14 @@
       "last"
     ],
     "semi": 0,
+    "prefer-arrow-callback": 2,
+    "arrow-spacing": 2,
+    "object-shorthand": 2,
     "no-eq-null": 0,
     "no-unused-expressions": 0,
     "no-loop-func": 2,
     "dot-notation": 0,
+    "no-trailing-spaces": 2,
     "valid-jsdoc": ["error", {
         "requireReturn": false,
         "requireReturnDescription": false,

Makefile

@@ -61,7 +61,7 @@ clean:
 	rm -rf perf/versions/
 
 lint:
-	eslint $(LINT_FILES)
+	eslint --fix $(LINT_FILES)
 
 # Compile the ES6 modules to singular bundles, and individual bundles
 build-bundle: build-modules $(UMD_BUNDLE)

lib/apply.js

@@ -1,5 +1,3 @@
-import slice from './internal/slice';
-
 /**
  * Creates a continuation function with some arguments already applied.
  *
@@ -45,10 +43,6 @@ import slice from './internal/slice';
  * two
  * three
  */
-export default function(fn/*, ...args*/) {
-    var args = slice(arguments, 1);
-    return function(/*callArgs*/) {
-        var callArgs = slice(arguments);
-        return fn.apply(null, args.concat(callArgs));
-    };
-};
+export default function(fn, ...args) {
+    return (...callArgs) => fn(...args,...callArgs);
+}

lib/asyncify.js

@@ -1,5 +1,6 @@
 import initialParams from './internal/initialParams';
 import setImmediate from './internal/setImmediate';
+import { isAsync } from './internal/wrapAsync'
 
 /**
  * Take a sync function and make it async, passing its return value to a
@@ -58,6 +59,14 @@ import setImmediate from './internal/setImmediate';
  * q.push(files);
  */
 export default function asyncify(func) {
+    if (isAsync(func)) {
+        return function (...args/*, callback*/) {
+            const callback = args.pop()
+            const promise = func.apply(this, args)
+            return handlePromise(promise, callback)
+        }
+    }
+
     return initialParams(function (args, callback) {
         var result;
         try {
@@ -67,25 +76,25 @@ export default function asyncify(func) {
         }
         // if result is Promise object
         if (result && typeof result.then === 'function') {
-            result.then(function(value) {
-                invokeCallback(callback, null, value);
-            }, function(err) {
-                invokeCallback(callback, err.message ? err : new Error(err));
-            });
+            return handlePromise(result, callback)
         } else {
             callback(null, result);
         }
     });
 }
 
+function handlePromise(promise, callback) {
+    return promise.then(value => {
+        invokeCallback(callback, null, value);
+    }, err => {
+        invokeCallback(callback, err.message ? err : new Error(err));
+    });
+}
+
 function invokeCallback(callback, error, value) {
     try {
         callback(error, value);
-    } catch (e) {
-        setImmediate(rethrow, e);
+    } catch (err) {
+        setImmediate(e => { throw e }, err);
     }
 }
-
-function rethrow(error) {
-    throw error;
-}

lib/auto.js

@@ -1,7 +1,5 @@
 import noop from './internal/noop';
 
-import forOwn from './internal/forOwn';
-import slice from './internal/slice';
 import once from './internal/once';
 import onlyOnce from './internal/onlyOnce';
 import wrapAsync from './internal/wrapAsync';
@@ -114,7 +112,8 @@ export default function (tasks, concurrency, callback) {
     // without the possibility of returning to an ancestor task
     var uncheckedDependencies = {};
 
-    forOwn(tasks, function (task, key) {
+    Object.keys(tasks).forEach(key => {
+        var task = tasks[key]
         if (!Array.isArray(task)) {
             // no dependencies
             enqueueTask(key, [task]);
@@ -131,14 +130,14 @@ export default function (tasks, concurrency, callback) {
         }
         uncheckedDependencies[key] = remainingDependencies;
 
-        dependencies.forEach(function (dependencyName) {
+        dependencies.forEach(dependencyName => {
             if (!tasks[dependencyName]) {
                 throw new Error('async.auto task `' + key +
                     '` has a non-existent dependency `' +
                     dependencyName + '` in ' +
                     dependencies.join(', '));
             }
-            addListener(dependencyName, function () {
+            addListener(dependencyName, () => {
                 remainingDependencies--;
                 if (remainingDependencies === 0) {
                     enqueueTask(key, task);
@@ -151,9 +150,7 @@ export default function (tasks, concurrency, callback) {
     processQueue();
 
     function enqueueTask(key, task) {
-        readyTasks.push(function () {
-            runTask(key, task);
-        });
+        readyTasks.push(() => runTask(key, task));
     }
 
     function processQueue() {
@@ -179,29 +176,27 @@ export default function (tasks, concurrency, callback) {
 
     function taskComplete(taskName) {
         var taskListeners = listeners[taskName] || [];
-        taskListeners.forEach(function (fn) {
-            fn();
-        });
+        taskListeners.forEach(fn => fn());
         processQueue();
     }
 
 
     function runTask(key, task) {
         if (hasError) return;
 
-        var taskCallback = onlyOnce(function(err, result) {
+        var taskCallback = onlyOnce((err, ...result) => {
             runningTasks--;
             if (err === false) {
                 canceled = true
                 return
             }
-            if (arguments.length > 2) {
-                result = slice(arguments, 1);
+            if (result.length < 2) {
+                result = result[0];
             }
             if (err) {
                 var safeResults = {};
-                forOwn(results, function(val, rkey) {
-                    safeResults[rkey] = val;
+                Object.keys(results).forEach(rkey => {
+                    safeResults[rkey] = results[rkey];
                 });
                 safeResults[key] = result;
                 hasError = true;
@@ -232,7 +227,7 @@ export default function (tasks, concurrency, callback) {
         while (readyToCheck.length) {
             currentTask = readyToCheck.pop();
             counter++;
-            getDependents(currentTask).forEach(function (dependent) {
+            getDependents(currentTask).forEach(dependent => {
                 if (--uncheckedDependencies[dependent] === 0) {
                     readyToCheck.push(dependent);
                 }
@@ -248,7 +243,8 @@ export default function (tasks, concurrency, callback) {
 
     function getDependents(taskName) {
         var result = [];
-        forOwn(tasks, function (task, key) {
+        Object.keys(tasks).forEach(key => {
+            const task = tasks[key]
             if (Array.isArray(task) && task.indexOf(taskName) >= 0) {
                 result.push(key);
             }

lib/autoInject.js

@@ -1,9 +1,8 @@
 import auto from './auto';
-import forOwn from './internal/forOwn';
 import wrapAsync from './internal/wrapAsync';
 import { isAsync } from './internal/wrapAsync';
 
-var FN_ARGS = /^(?:async\s+)?(function)?\s*[^\(]*\(\s*([^\)]*)\)/m;
+var FN_ARGS = /^(?:async\s+)?(function)?\s*[^(]*\(\s*([^)]*)\)/m;
 var FN_ARG_SPLIT = /,/;
 var FN_ARG = /(=.+)?(\s*)$/;
 var STRIP_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg;
@@ -12,7 +11,7 @@ function parseParams(func) {
     func = func.toString().replace(STRIP_COMMENTS, '');
     func = func.match(FN_ARGS)[2].replace(' ', '');
     func = func ? func.split(FN_ARG_SPLIT) : [];
-    func = func.map(function (arg){
+    func = func.map((arg) => {
         return arg.replace(FN_ARG, '').trim();
     });
     return func;
@@ -103,16 +102,17 @@ function parseParams(func) {
 export default function autoInject(tasks, callback) {
     var newTasks = {};
 
-    forOwn(tasks, function (taskFn, key) {
+    Object.keys(tasks).forEach(key => {
+        var taskFn = tasks[key]
         var params;
         var fnIsAsync = isAsync(taskFn);
         var hasNoDeps =
             (!fnIsAsync && taskFn.length === 1) ||
             (fnIsAsync && taskFn.length === 0);
 
         if (Array.isArray(taskFn)) {
-            params = taskFn.slice(0, -1);
-            taskFn = taskFn[taskFn.length - 1];
+            params = [...taskFn];
+            taskFn = params.pop();
 
             newTasks[key] = params.concat(params.length > 0 ? newTask : taskFn);
         } else if (hasNoDeps) {
@@ -131,11 +131,9 @@ export default function autoInject(tasks, callback) {
         }
 
         function newTask(results, taskCb) {
-            var newArgs = params.map(function (name) {
-                return results[name];
-            });
+            var newArgs = params.map(name => results[name])
             newArgs.push(taskCb);
-            wrapAsync(taskFn).apply(null, newArgs);
+            wrapAsync(taskFn)(...newArgs);
         }
     });
 

lib/compose.js

@@ -1,5 +1,4 @@
 import seq from './seq';
-import slice from './internal/slice';
 
 /**
  * Creates a function which is a composition of the passed asynchronous
@@ -36,6 +35,6 @@ import slice from './internal/slice';
  *     // result now equals 15
  * });
  */
-export default function(/*...args*/) {
-    return seq.apply(null, slice(arguments).reverse());
-};
+export default function(...args) {
+    return seq(...args.reverse());
+}

lib/concatLimit.js

@@ -1,10 +1,7 @@
 import noop from './internal/noop';
 import wrapAsync from './internal/wrapAsync';
-import slice from './internal/slice';
 import mapLimit from './mapLimit';
 
-var _concat = Array.prototype.concat;
-
 /**
  * The same as [`concat`]{@link module:Collections.concat} but runs a maximum of `limit` async operations at a time.
  *
@@ -26,16 +23,16 @@ var _concat = Array.prototype.concat;
 export default function(coll, limit, iteratee, callback) {
     callback = callback || noop;
     var _iteratee = wrapAsync(iteratee);
-    mapLimit(coll, limit, function(val, callback) {
-        _iteratee(val, function(err /*, ...args*/) {
+    mapLimit(coll, limit, (val, callback) => {
+        _iteratee(val, (err, ...args) => {
             if (err) return callback(err);
-            return callback(null, slice(arguments, 1));
+            return callback(null, args);
         });
-    }, function(err, mapResults) {
+    }, (err, mapResults) => {
         var result = [];
         for (var i = 0; i < mapResults.length; i++) {
             if (mapResults[i]) {
-                result = _concat.apply(result, mapResults[i]);
+                result = result.concat(...mapResults[i]);
             }
         }
 

lib/constant.js

@@ -1,5 +1,3 @@
-import slice from './internal/slice';
-
 /**
  * Returns a function that when called, calls-back with the values provided.
  * Useful as the first function in a [`waterfall`]{@link module:ControlFlow.waterfall}, or for plugging values in to
@@ -42,11 +40,9 @@ import slice from './internal/slice';
  *     //...
  * }, callback);
  */
-export default function(/*...values*/) {
-    var values = slice(arguments);
-    var args = [null].concat(values);
-    return function (/*...ignoredArgs, callback*/) {
-        var callback = arguments[arguments.length - 1];
-        return callback.apply(this, args);
+export default function(...args) {
+    return function (...ignoredArgs/*, callback*/) {
+        var callback = ignoredArgs.pop();
+        return callback(null, ...args);
     };
-};
+}

lib/detect.js

@@ -1,7 +1,5 @@
-import identity from './internal/identity';
 import createTester from './internal/createTester';
 import doParallel from './internal/doParallel';
-import findGetResult from './internal/findGetResult';
 
 /**
  * Returns the first value in `coll` that passes an async truth test. The
@@ -38,4 +36,4 @@ import findGetResult from './internal/findGetResult';
  *     // result now equals the first file in the list that exists
  * });
  */
-export default doParallel(createTester(identity, findGetResult));
+export default doParallel(createTester(bool => bool, (res, item) => item));

lib/detectLimit.js

@@ -1,7 +1,5 @@
-import identity from './internal/identity';
 import createTester from './internal/createTester';
 import doParallelLimit from './internal/doParallelLimit';
-import findGetResult from './internal/findGetResult';
 
 /**
  * The same as [`detect`]{@link module:Collections.detect} but runs a maximum of `limit` async operations at a
@@ -25,4 +23,4 @@ import findGetResult from './internal/findGetResult';
  * (iteratee) or the value `undefined` if none passed. Invoked with
  * (err, result).
  */
-export default doParallelLimit(createTester(identity, findGetResult));
+export default doParallelLimit(createTester(bool => bool, (res, item) => item));

lib/doDuring.js

@@ -1,5 +1,4 @@
 import noop from './internal/noop';
-import slice from './internal/slice';
 import onlyOnce from './internal/onlyOnce';
 import wrapAsync from './internal/wrapAsync';
 
@@ -28,13 +27,11 @@ export default function doDuring(fn, test, callback) {
     var _fn = wrapAsync(fn);
     var _test = wrapAsync(test);
 
-    function next(err/*, ...args*/) {
+    function next(err, ...args) {
         if (err) return callback(err);
         if (err === false) return;
-        var args = slice(arguments, 1);
-        args.push(check);
-        _test.apply(this, args);
-    };
+        _test(...args, check);
+    }
 
     function check(err, truth) {
         if (err) return callback(err);