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js class this在new与静态引用时所指不同
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js class this在new与静态引用时所指不同
this在这里的表现也跟func样跟着谁说叫谁老板的,与function.call(“this”概念一样。
简单的一个类
class a{
static a = "static-a";
b = "ins-b";
constructor(){
console.log('new',this.a,this.b,this);
}
static fn(){
console.log('static',this.a,this.b,this);
}
}
- new用法
new a();
时输出如后:new undefined ins-b a {b: "ins-b"}
,选择性失明,static的东西与被抛弃了; - static用法:
a.fn();
,输出结果如下:
static static-a undefined class a{
static a = "static-a";
b = "ins-b";
constructor(){
console.log('new',this.a,this.b,this);
}
static fn(){
console.log('static',this.a,this.b,this);
}
}
同样,new的东西被选择性抛弃;
ok,通过上面2个例子,我们可以明确了解到,this,就是指向当前这个使用的对象如new出来的实例,或是static
发表于 2019.07.16 14:50:24
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