removing hokum from _.bind

Author: jashkenas

test/functions.js

@@ -28,20 +28,15 @@
     func = _.bind(func, this, 'hello', 'moe', 'curly');
     equal(func(), 'hello: moe curly', 'the function was partially applied in advance and can accept multiple arguments');
 
-    func = function(context, message) { equal(this, context, message); };
-    _.bind(func, 0, 0, 'can bind a function to `0`')();
-    _.bind(func, '', '', 'can bind a function to an empty string')();
-    _.bind(func, false, false, 'can bind a function to `false`')();
-
     // These tests are only meaningful when using a browser without a native bind function
     // To test this with a modern browser, set underscore's nativeBind to undefined
     var F = function () { return this; };
     var boundf = _.bind(F, {hello: 'moe curly'});
     var Boundf = boundf; // make eslint happy.
     var newBoundf = new Boundf();
-    equal(newBoundf.hello, undefined, 'function should not be bound to the context, to comply with ECMAScript 5');
+    equal(newBoundf.hello, 'moe curly', 'function should not be bound to the context, because this ain\'t ECMA5');
     equal(boundf().hello, 'moe curly', "When called without the new operator, it's OK to be bound to the context");
-    ok(newBoundf instanceof F, 'a bound instance is an instance of the original function');
+    ok(!(newBoundf instanceof F), 'a bound instance is not an instance of the original function');
 
     throws(function() { _.bind('notafunction'); }, TypeError, 'throws an error when binding to a non-function');
   });
@@ -62,20 +57,6 @@
 
     func = _.partial(function() { return typeof arguments[2]; }, _, 'b', _, 'd');
     equal(func('a'), 'undefined', 'unfilled placeholders are undefined');
-
-    // passes context
-    function MyWidget(name, options) {
-      this.name = name;
-      this.options = options;
-    }
-    MyWidget.prototype.get = function() {
-      return this.name;
-    };
-    var MyWidgetWithCoolOpts = _.partial(MyWidget, _, {a: 1});
-    var widget = new MyWidgetWithCoolOpts('foo');
-    ok(widget instanceof MyWidget, 'Can partially bind a constructor');
-    equal(widget.get(), 'foo', 'keeps prototype');
-    deepEqual(widget.options, {a: 1});
   });
 
   test('bindAll', function() {

underscore.js

@@ -112,16 +112,6 @@
     };
   };
 
-  // An internal function for creating a new object that inherits from another.
-  var baseCreate = function(prototype) {
-    if (!_.isObject(prototype)) return {};
-    if (nativeCreate) return nativeCreate(prototype);
-    Ctor.prototype = prototype;
-    var result = new Ctor;
-    Ctor.prototype = null;
-    return result;
-  };
-
   // Helper for collection methods to determine whether a collection
   // should be iterated as an array or as an object
   // Related: http://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength
@@ -688,16 +678,6 @@
   // Function (ahem) Functions
   // ------------------
 
-  // Determines whether to execute a function as a constructor
-  // or a normal function with the provided arguments
-  var executeBound = function(sourceFunc, boundFunc, context, callingContext, args) {
-    if (!(callingContext instanceof boundFunc)) return sourceFunc.apply(context, args);
-    var self = baseCreate(sourceFunc.prototype);
-    var result = sourceFunc.apply(self, args);
-    if (_.isObject(result)) return result;
-    return self;
-  };
-
   // Create a function bound to a given object (assigning `this`, and arguments,
   // optionally). Delegates to **ECMAScript 5**'s native `Function.bind` if
   // available.
@@ -706,7 +686,7 @@
     if (!_.isFunction(func)) throw new TypeError('Bind must be called on a function');
     var args = slice.call(arguments, 2);
     return function bound() {
-      return executeBound(func, bound, context, this, args.concat(slice.call(arguments)));
+      return func.apply(context || this, args.concat(slice.call(arguments)));
     };
   };
 
@@ -722,7 +702,7 @@
         args[i] = boundArgs[i] === _ ? arguments[position++] : boundArgs[i];
       }
       while (position < arguments.length) args.push(arguments[position++]);
-      return executeBound(func, bound, this, this, args);
+      return func.apply(this, args);
     };
   };