set default values for each functions. Fixes #667

3 files changed, 56 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f6960bc..d637ab4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@ New Features:
 - `cargo` now supports all of the same methods and event callbacks as `queue`.
 - Added `ensureAsync` - A wrapper that ensures an async function calls its callback on a later tick. (#769)
 - Optimized `map`, `eachOf`, and `waterfall` families of functions
+- Passing a `null` or `undefined` array to `map`, `each`, `parallel` and families will be treated as an empty array (#667).
 - Reduced file size by 4kb, (minified version by 1kb) 
 - Added code coverage through `nyc` and `coveralls` (#768)
 
diff --git a/lib/async.js b/lib/async.js
index fd7a953..68b9c54 100644
--- a/lib/async.js
+++ b/lib/async.js
@@ -207,6 +207,7 @@
     async.forEachOf =
     async.eachOf = function (object, iterator, callback) {
         callback = callback || noop;
+        object = object || [];
         var size = object.length || _keys(object).length;
         var completed = 0;
         if (!size) {
@@ -232,6 +233,7 @@
     async.forEachOfSeries =
     async.eachOfSeries = function (obj, iterator, callback) {
         callback = callback || noop;
+        obj = obj || [];
         var nextKey = _keyIterator(obj);
         function iterate() {
             var sync = true;
@@ -269,6 +271,7 @@
 
         return function (obj, iterator, callback) {
             callback = callback || noop;
+            obj = obj || [];
             var nextKey = _keyIterator(obj);
             if (limit <= 0) {
                 return callback(null);
diff --git a/test/test-async.js b/test/test-async.js
index bdb8147..ce2fc8d 100755
--- a/test/test-async.js
+++ b/test/test-async.js
@@ -1780,6 +1780,27 @@ exports['map'] = {
     setTimeout(test.done, 50);
 },
 
+'map undefined array': function(test){
+    test.expect(2);
+    async.map(undefined, function(x, callback){
+        callback();
+    }, function(err, result){
+        test.equals(err, null);
+        test.same(result, []);
+    });
+    setTimeout(test.done, 50);
+},
+
+'map object': function (test) {
+    async.map({a: 1, b: 2, c: 3}, function (val, callback) {
+        callback(null, val * 2);
+    }, function (err, result) {
+        if (err) throw err;
+        test.same(result, {a: 2, b: 4, c: 6});
+        test.done();
+    });
+},
+
 'mapSeries': function(test){
     var call_order = [];
     async.mapSeries([1,3,2], mapIterator.bind(this, call_order), function(err, results){
@@ -1800,6 +1821,26 @@ exports['map'] = {
     setTimeout(test.done, 50);
 },
 
+'mapSeries undefined array': function(test){
+    test.expect(2);
+    async.mapSeries(undefined, function(x, callback){
+        callback();
+    }, function(err, result){
+        test.equals(err, null);
+        test.same(result, []);
+    });
+    setTimeout(test.done, 50);
+},
+
+'mapSeries object': function (test) {
+    async.mapSeries({a: 1, b: 2, c: 3}, function (val, callback) {
+        callback(null, val * 2);
+    }, function (err, result) {
+        if (err) throw err;
+        test.same(result, {a: 2, b: 4, c: 6});
+        test.done();
+    });
+},
 
 'mapLimit': function(test){
     var call_order = [];
@@ -1823,6 +1864,17 @@ exports['map'] = {
     setTimeout(test.done, 25);
 },
 
+'mapLimit undefined array': function(test){
+    test.expect(2);
+    async.mapLimit(undefined, 2, function(x, callback){
+        callback();
+    }, function(err, result){
+        test.equals(err, null);
+        test.same(result, []);
+    });
+    setTimeout(test.done, 50);
+},
+
 'mapLimit limit exceeds size': function(test){
     var call_order = [];
     async.mapLimit([0,1,2,3,4,5,6,7,8,9], 20, mapIterator.bind(this, call_order), function(err, results){