Javascript 在 Child 中调用 Parent 构造函数（原型继承） - 它是如何工作的？

我知道它有效，但我不知道为什么以及如何。有哪些机制？

// Parent constructor
function Parent(name){
  this.name = name || "The name property is empty";
}

// Child constructor
function Child(name){
  this.name = name;
}

// Originaly, the Child "inherit" everything from the Parent, also the name property, but in this case
// I shadowing that with the name property in the Child constructor.
Child.prototype = new Parent();

// I want to this: if I dont set a name, please inherit "The name property is empty" from the 
// Parent constructor. But I know, it doesn't work because I shadow it in the Child.
var child1 = new Child("Laura");
var child2 = new Child();

//And the result is undefined (of course) 
console.log(child1.name, child2.name);  //"Laura", undefined

我知道我需要什么，call() or the apply()方法。致电“超一流" (the Parent构造函数）来自Child，并通过this对象和论点name对此。有用：

function Parent(name){
  this.name = name || "The name property is empty";
}

function Child(name){
  // Call the "super class" but WHAT AM I DO? How does it work? I don't understand the process, I lost the line.
  Parent.call(this, name);
}

Child.prototype = new Parent();

var child1 = new Child("Laura");
var child2 = new Child();

console.log(child1.name, child2.name); // "Laura", "The name property is empty"

它工作完美，但我不明白会发生什么。我失去了this在我的脑海里，我无法遵循这个过程call()方法。是否从复制构造函数体Parent to the Child或者是什么？哪里是this目的？为什么它有效？

请帮忙描述一下过程，我不太明白。

首先，停止做Child.prototype = new Parent();用于继承，除非您的浏览器不支持任何其他替代方案。这是一种非常糟糕的风格，并且可能会产生不良的副作用，因为它实际上运行构造函数逻辑。

您可以使用Object.create现在在每个现代浏览器中。

Child.prototype = Object.create(Parent.prototype);

请注意，此后您还应该修复constructor的财产Child.prototype以便它正确地指向Child而不是Parent.

Child.prototype.constructor = Child;

接下来，如何call作品？出色地call允许指定哪个对象将被引用this函数执行时的关键字。

function Child(name){
  //When calling new Child(...), 'this' references the newly created 'Child' instance

  //We then apply the 'Parent' constructor logic to 'this', by calling the 'Parent' function
  //using 'call', which allow us to specify the object that 'this' should reference 
  //during the function execution.
  Parent.call(this, name);
}