Question

我无法理解第4行如果我像derive.constructor.prototype那样写，将发生错误。

而且，什么是base.apply(derive, baseArgs);？
我认为我可以做base(baseArg)我不能那样做。

function initializeBase(derive, base, baseArgs) {
  base.apply(derive, baseArgs);
  for(var prop in base.prototype) {
    var proto = derive.constructor.prototype;
    if(!proto[prop]) {
      proto[prop] = base.prototype[prop];
    }
  }
}

var Member = function(firstName, lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
};

Member.prototype.getName = function() {
    return this.firstName + ' ' + this.lastName;
};

var SpecialMember = function(firstName, lastName, role) {
    initializeBase(this, Member, [firstName, lastName]);

    this.role = role;
};

SpecialMember.prototype.isAdministrator = function() {
    return (this.role == 'Administrator');
};

var mem = new SpecialMember('Kotaro', 'Hayafune', 'Administrator');
document.writeln('Name: ' + mem.getName() + '<br>');
document.writeln('Administrator: ' + mem.isAdministrator());

Answer 1

不确定你的变量包含在哪里，但通常如果你想要原型你会写：

var proto = derive.prototype;

如果你想要你写的构造函数：

var constr = derive.prototype.constructor;

JavaScript继承constructor.prototype

1 个答案: