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[实践系列]模拟实现new操作符 #6

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webfansplz opened this issue Mar 5, 2019 · 1 comment

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webfansplz commented Mar 5, 2019

new操作符做了什么?

创建一个新对象
新对象继承了构造函数的原型
构造函数的this指向新对象,并执行构造函数。
最后隐式的返回this,即新对象。

如果我们在构造函数中进行显式返回,会发生什么?

由此我们可以得出结论:构造函数如果返回基本类型,则会忽略,还是返回原来的this(新对象).如果返回的是引用类型,则会对该返回值进行处理,返回该返回值。

new操作符的模拟实现

知道new操作符做了什么,我们要实现就不难了,直接上代码!

webfansplz added the javascript label

zhw2590582 commented Mar 19, 2019

假如res刚好等于null，理应也返回o的。

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