Merge pull request #2843 from jgonggrijp/array-method-null-check

Author: jgonggrijp

modules/index.js

@@ -1653,8 +1653,12 @@ each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(
   var method = ArrayProto[name];
   _.prototype[name] = function() {
     var obj = this._wrapped;
-    method.apply(obj, arguments);
-    if ((name === 'shift' || name === 'splice') && obj.length === 0) delete obj[0];
+    if (obj != null) {
+      method.apply(obj, arguments);
+      if ((name === 'shift' || name === 'splice') && obj.length === 0) {
+        delete obj[0];
+      }
+    }
     return chainResult(this, obj);
   };
 });
@@ -1663,7 +1667,9 @@ each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(
 each(['concat', 'join', 'slice'], function(name) {
   var method = ArrayProto[name];
   _.prototype[name] = function() {
-    return chainResult(this, method.apply(this._wrapped, arguments));
+    var obj = this._wrapped;
+    if (obj != null) obj = method.apply(obj, arguments);
+    return chainResult(this, obj);
   };
 });
 

test/chaining.js

@@ -96,4 +96,14 @@
     assert.strictEqual('' + wrapped, '512');
   });
 
+  QUnit.test('wrapper methods handle undefined and null', function(assert) {
+    var w1 = _(), w2 = _(null);
+    _.each([w1, w2], function(wrapped) {
+      assert.equal(wrapped.extend({a: 1}), void 0);
+      assert.equal(wrapped.first(), void 0);
+      assert.equal(wrapped.push(1), void 0);
+      assert.equal(wrapped.concat([1]), void 0);
+    });
+  });
+
 }());