Javascript由两个子类继承

Question

我有这个代码:

var first = function() {
  this.loc = '1';
  this.test = function() {
    console.log('first ' + this.loc);
  }
}

var second = function() {
  var me = this;

  this.loc = '2';
  this.test = function() {
    console.log('second ' + this.loc);
    Object.getPrototypeOf(me).test.call(me);
  }
}

second.prototype = new first();

var third = function() {
  var me = this;

  this.loc = '3';
  this.test = function() {
    console.log('third ' + this.loc);
    Object.getPrototypeOf(me).test.call(me);
  }
}

third.prototype = new second();

var t = new third();
t.test();

它将输出:

third 3
second 3
first 2

如何让它输出:

third 3
second 3
first 3

所以我想用最后一个继承类覆盖第一类 loc 值。

Answer 1

更改 thisArg(signature fun.call(thisArg[, arg1[, arg2[, ...]]])) 为 第二个 code> 从 me 到 this 的对象函数调用:

...
var second = function() {
    var me = this;

    this.loc = '2';
    this.test = function() {
        console.log('second ' + this.loc);
        Object.getPrototypeOf(me).test.call(this); // <--
    }
}
...

进展如何:

第一次，test()函数在third实例上被调用，输出“third 3”

然后，从同一个third上的第二实例(作为第三原型(prototype))调用test函数> 实例通过 Object.getPrototypeOf(me).test.call(me);

当test函数执行时this关键字应该指向third实例并传递给进一步的test()调用