JavaScript异步问题如何解决
//下面代码存在两个问题，只允许修改Obj构造函数及其原型使程序正常执行
function initData(callback){
setTimeout(()=>{
callback("hello")
},2000)
}
function Obj(){
this.o = null ;
this.init();
}
Obj.prototype = {
init :function(){
initData(this.callback)
},
callback:function(name){
this.o = {"name":name}; //问题2，此时this指向的是window对象，如何指向通过Obj产生的实例
},
getName:function(){
return this.o.name;
}
}
var obj = new Obj();
obj.getName(); //问题1，这里会报错
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解决方案
function initData(callback,that) {
setTimeout(() => {
callback.call(that,"hello")
}, 2000)
}
function Obj(loaded) {
this.o = null;
this.loaded = loaded;
this.init();
}
Obj.prototype = {
init: function () {
initData(this.callback,this)
},
callback: function (name) {
this.o = { "name": name }; //问题2，此时this指向的是window对象，如何指向通过Obj产生的实例
typeof this.loaded =="function" && this.loaded();
},
getName: function () {
return this.o.name;
}
}
var obj = new Obj(afterLoaded);
function afterLoaded(){
console.log(obj.getName());
}
