已废弃
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

`__noSuchMethod__` 属性曾经是指当调用某个对象里不存在的方法时即将被执行的函数，但是现在这个函数已经不可用。

`在__noSuchMethod__` 属性被移除之后，ECMAScript 2015 (ES6) 规范转而采用 `Proxy` 对象， 可以实现下面的效果（以及更多）。

## 语法

    obj.__noSuchMethod__ = fun

### 参数

`fun`
  函数形式如下：

      function (id, args) { . . . }

  `id`
    调用的不存在的方法名
  `args`
    传递给该方法的参数数组

## 描述

默认情况喜爱，试图调用对象上不存在的方法其结果是在`TypeError`上抛出异常，这种行为可以在

By default, an attempt to call a method that doesn't exist on an object results in a `TypeError` being thrown. This behavior can be circumvented by defining a function at that object's `__noSuchMethod__` member. The function takes two arguments, the first is the name of the method attempted and the second is an array of the arguments that were passed in the method call. The second argument is an actual array (that is, it inherits through the `Array.prototype` chain) and not the array-like arguments object.

If this method cannot be called, either as if `undefined` by default, if deleted, or if manually set to a non-function, the JavaScript engine will revert to throwing `TypeError`s.

## Examples

### Simple test of `__noSuchMethod__`

    var o = {
      __noSuchMethod__: function(id, args) {
                          console.log(id, '(' + args.join(', ') + ')');
                        }
    };

    o.foo(1, 2, 3);
    o.bar(4, 5);
    o.baz();

    // Output
    // foo (1, 2, 3)
    // bar (4, 5)
    // baz ()

### Using `__noSuchMethod__` to simulate multiple inheritance

An example of code that implements a primitive form of multiple inheritance is shown below.

    // Doesn't work with multiple inheritance objects as parents
    function noMethod(name, args) {
      var parents = this.__parents_;

      // Go through all parents
      for (var i = 0; i < parents.length; i++) {
        // If we find a function on the parent, we call it
        if (typeof parents[i][name] == "function") {
          return parents[i][name].apply(this, args);
        }
      }

      // If we get here, the method hasn't been found
      throw new TypeError;
    }

    // Used to add a parent for multiple inheritance
    function addParent(obj, parent) {
      // If the object isn't initialized, initialize it
      if (!obj.__parents_) {
        obj.__parents_ = [];
        obj.__noSuchMethod__ = noMethod;
      }

      // Add the parent
      obj.__parents_.push(parent);
    }

An example of using this idea is shown below.

    // Example base class 1
    function NamedThing(name){
      this.name=name;
    }

    NamedThing.prototype = {
      getName: function() { return this.name; },
      setName: function(newName) { this.name = newName; }
    }

    // Example base class 2
    function AgedThing(age) {
      this.age = age;
    }

    AgedThing.prototype = {
      getAge: function() { return this.age; },
      setAge: function(age) { this.age = age; }
    }

    // Child class. inherits from NamedThing and AgedThing
    // as well as defining address
    function Person(name, age, address){
      addParent(this, NamedThing.prototype);
      NamedThing.call(this, name);
      addParent(this, AgedThing.prototype);
      AgedThing.call(this, age);
      this.address = address;
    }

    Person.prototype = {
      getAddr: function() { return this.address; },
      setAddr: function(addr) { this.address = addr; }
    }

    var bob = new Person("bob", 25, "New York");

    console.log("getAge is " + (("getAge" in bob) ? "in" : "not in") + " bob");
    // getAge is not in bob

    console.log("bob's age is: " + bob.getAge());
    // bob's age is: 25

    console.log("getName is " + (("getName" in bob) ? "in" : "not in") + " bob");
    // getName is not in bob

    console.log("bob's name is: " + bob.getName());
    // bob's name is: bob

    console.log("getAddr is " + (("getAddr" in bob) ? "in" : "not in") + " bob");
    // getAddr is in bob

    console.log("bob's address is: " + bob.getAddr());
    // bob's address is: New York

## Specifications

Not part of any specifications. This feature has been removed, see bug 683218.

## Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

- Desktop
- Mobile

Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari
--- | --- | --- | --- | --- | ---
Basic support | 未实现 | 未实现 [1] | 未实现 | 未实现 | 未实现

Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile
--- | --- | --- | --- | --- | --- | ---
Basic support | 未实现 | 未实现 | 未实现 [1] | 未实现 | 未实现 | 未实现

[1] This feature was implemented until version 43.