javascript - js 闭包问题
本文介绍了javascript - js 闭包问题的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
问 题
var name = "The Window";
var object = {
name : "My Object",
getNameFunc : function(){
return function(){
return this.name;
};
}
};
alert(object.getNameFunc()());
var name = "The Window";
var object = {
name : "My Object",
getNameFunc : function(){
var that = this;
return function(){
return that.name;
};
}
};
alert(object.getNameFunc()());
知道闭包是要在函数外部读取内部的变量,但是这个代码还是不咋理解啊= =
解决方案
var name = "The Window";//定义全局变量name,而在浏览器中,全局变量会自动成为window的属性.
var object = {
name : "My Object",
getNameFunc : function(){
return function(){
return this.name;//这里的this指向window,所以返回window.name
};
}
};
alert(object.getNameFunc()());
var name = "The Window";
var object = {
name : "My Object",
getNameFunc : function(){
var that = this;
return function(){
return that.name;//而这里用that保存了本对象this值
};
}
};
alert(object.getNameFunc()());
//所以这两段代码对比是为了说明函数内的嵌套函数的this指向的是顶级变量window.
既然你提到了闭包,那你看看这段代码,自己先思考下,再运行,希望帮到你~
var oPerson = { name: 'john' };
(function(oTeacher) {
window.getTeacher= function() {
console.log(oTeacher);
};
}(oPerson));
window.getTeacher();
oPerson.surname = 'doe';
window.getTeacher();
oPerson = { name: 'mary', surname: 'sullivan' };
window.getTeacher();
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