在javascript中为什么使用"var that = this" [英] in javascript why use " var that = this "

问题描述

我是javascript新手

hi i am new with javascript

使用此行有什么好处

var that = this

一个例子

function Person( firstname, lastname, age ) {

    this.firstname = firstname;

    this.lastname = lastname;

    this.age = age;

    getfullname = function() {

        return firstname + " " + lastname;
    };

    var that = this;


    this.sayHi = function() {

        document.write( "Hi my name is " + getfullname() + " and I am " + that.age + "years old.");

    };
}

谢谢

推荐答案

因为内部函数 this 与外部函数不同，因此将其别名为，您可以确保与同一个对象通话.

because in the inner function this will not be the same object as in the outer, so by aliasing it to that you can make sure you are talking to the same object.

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