JavaScript基本问题. [英] Javascript basic question.

问题描述

大家好，

我是javascript的初学者.

Hi All,

I am beginner to javascript.

    var ButtonHandler = function()
    {
        var me = this;
        
        this.click = function()
        {
            alert("Click");
            me.meClick(); // How It can find "me"!!?
        };
        this.meClick = function()
        {
            alert("meClick");
        };
    }; 
    var b = new ButtonHandler(); // me created and destroyed.

    function onBtnclick()
    {
        b.click();
        //ButtonHandler.prototype.click();
    }
}

我将onBtnclick绑定到按钮单击.

我的困惑是在创建 var b 时，"me"已创建并销毁.

但是当我单击按钮时，它如何找到我"?.


对不起，我的英语
谢谢大家.

I bind onBtnclick to button click.

My confusion is at creation of var b "me" is created and destroyed.

but when i click button,How it finds "me"?.


Sorry for my english
Thanks all.

推荐答案

这就是所谓的闭包 [ ^ ].在定义要分配给this.click的函数时，周围环境中定义的所有变量都可以从该函数定义中获取.

在此处查看: http://www.javascriptkit.com/javatutors/closures.shtml [

This is what is called a closure[^] in computer science. As the function is being defined that is being assigned to this.click all the variables that are defined in the surrounding environment are reachabel from within that function definition.

Seeh here: http://www.javascriptkit.com/javatutors/closures.shtml[^]

— Manfred

在创建变量b时创建并销毁了"me".
"me"何时何地被销毁?

只要"b"可用，对象就存在，它的成员也是如此.对? me没有被破坏，因此它存在.

at creation of var b "me" is created and destroyed.
When and where did ''me'' was destroyed?

As long as ''b'' is available, object exists and so does it''s members. Right? me was not destroyed and so it exists.

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