fix(isArrayLike): recognize empty instances of an Array subclass

gkalpak · petebacondarwin · commit 323f9ab73696 · 2016-01-07T19:43:49.000Z
Fixes #13560 Closes #13708
diff --git a/src/Angular.js b/src/Angular.js
@@ -215,7 +215,8 @@ function isArrayLike(obj) {
   // NodeList objects (with `item` method) and
   // other objects with suitable length characteristics are array-like
   return isNumber(length) &&
-    (length >= 0 && (length - 1) in obj || typeof obj.item == 'function');
+    (length >= 0 && ((length - 1) in obj || obj instanceof Array) || typeof obj.item == 'function');
+
 }
 
 /**
diff --git a/test/AngularSpec.js b/test/AngularSpec.js
@@ -1119,17 +1119,38 @@ describe('angular', function() {
     });
 
     it('should return true if passed a nodelist', function() {
-      var nodes = document.body.childNodes;
-      expect(isArrayLike(nodes)).toBe(true);
+      var nodes1 = document.body.childNodes;
+      expect(isArrayLike(nodes1)).toBe(true);
+
+      var nodes2 = document.getElementsByTagName('nonExistingTagName');
+      expect(isArrayLike(nodes2)).toBe(true);
     });
 
     it('should return false for objects with `length` but no matching indexable items', function() {
-      var obj = {
+      var obj1 = {
         a: 'a',
         b:'b',
         length: 10
       };
-      expect(isArrayLike(obj)).toBe(false);
+      expect(isArrayLike(obj1)).toBe(false);
+
+      var obj2 = {
+        length: 0
+      };
+      expect(isArrayLike(obj2)).toBe(false);
+    });
+
+    it('should return true for empty instances of an Array subclass', function() {
+      function ArrayLike() {}
+      ArrayLike.prototype = Array.prototype;
+
+      var arrLike = new ArrayLike();
+      expect(arrLike.length).toBe(0);
+      expect(isArrayLike(arrLike)).toBe(true);
+
+      arrLike.push(1, 2, 3);
+      expect(arrLike.length).toBe(3);
+      expect(isArrayLike(arrLike)).toBe(true);
     });
   });
 

Original file line number	Diff line number	Diff line change
`@@ -215,7 +215,8 @@ function isArrayLike(obj) {`
`215`	`215`	// NodeList objects (with `item` method) and
`216`	`216`	`// other objects with suitable length characteristics are array-like`
`217`	`217`	`return isNumber(length) &&`
`218`		`- (length >= 0 && (length - 1) in obj \|\| typeof obj.item == 'function');`
	`218`	`+ (length >= 0 && ((length - 1) in obj \|\| obj instanceof Array) \|\| typeof obj.item == 'function');`
	`219`	`+`
`219`	`220`	`}`
`220`	`221`
`221`	`222`	`/**`