Question

为什么这指向父类，而不指向窗口对象？这不是Klass函数内部的。

function Class() {
    function Klass() {
        this.color="blue"
    }
    Klass.prototype.value = this; // when called this is pointing to Class
    console.log(this) // "Class"
    return Klass;
}

var One = new Class(); // new constructor is returned
var Two = new One(); // creating new object
Two.value 
    - Class  // why ?

Answer 1

Two.value instanceof Class // true

Two.value包含Class的实例，而不是对Class的引用。

Answer 2

function Class() {
    function Klass() {
        this.color="blue"
    }
    Klass.prototype.value = this; // this is in a closure
    console.log(this) // "Class"
    return Klass;
}

var One = new Class(); // new constructor is returned
var Two = new One(); // creating new object
Two.value 
    - Class  // this is always refer to "One"

当返回另一个构造函数时，从Javascript构造函数返回this的值

2 个答案: