JavaScript this 范围

看例子

 <script type="text/javascript">
        var f = function () {
            name = 'hongda';
            age = 27;
            say = function () {
                console.log(this.name + "||" + this.age);
            }
        }
        var method = function () {
            name = 'hongda2';
            age = 272;
            say = function () {
                console.log(this.name + "||" + this.age);
            }
        }
    </script>

由此可以看出这些name,age,say都是全局的，由window调用，say方法中的this就是window

 <script type="text/javascript">
        var f = function () {
            this.name = 'hongda';
            this.age = 27;
            this.say = function () {
                console.log(this.name + "||" + this.age);
            }
        }
    </script>

调用的对象是f的实例

 <script type="text/javascript">
       var f = function () {
           name = 'hongda';
           age = 27;
           say = function () {
               console.log(this.name + "||" + this.age);
           }
       }
       var method = function () {
           var name = 'hongda2';
           var age = 272;
           var say = function () {
               console.log(this.name + "||" + this.age);
           }
       }
    </script>

发现method中的变量前有了 var,表示就在method这个范围内

下面将证明method中的name,age,say是局部的

发现method()实例化以后，全局的变量name,age,say没有发生变化

下面个例子可以看出function即是类，又是方法

 <script type="text/javascript">
       var f = function () {
           this.name = 'hongda';
           this.age = 27;
           this.say = function () {
               console.log(this.name + "||" + this.age);
           }
       }
    </script>

var ff=new f(); f()是类

window.f()；  f()是方法