我最近一直在研究 Javascript 原型，可以理解理论，并相信它对我理解语言非常有用，但不能完全让以下工作......
var player = function(){//Declarations here};
var super_player.prototype = new player();
每个编译器/检查器都会在第 2 行标记一个“缺少分号”错误。 我很难过，但相信我忽略了一些非常简单的事情。
有人能指出正确的方向吗？
【问题讨论】：
标签： javascript class inheritance prototype
你想做类似的事情
function Player() {
// player things here
}
Player.prototype = new SuperPlayer(); // get all the things on SuperPlayer prototype
Player.prototype.constructor = Player;
假设 SuperPlayer 是 Player 的超类。
edit -- 如果 SuperPlayer 是更好的播放器，即 Player 的子类，只需颠倒上述模式即可
function SuperPlayer() {
// super player things here
}
SuperPlayer.prototype = new Player(); // get all the things on Player prototype
SuperPlayer.prototype.constructor = SuperPlayer; // the above line changed the constructor; change it back
我无法从你写的内容中看出 SuperPlayer 是否是一个子类。此外，其他答案指出，由于评论，您发布的代码在语法上被破坏了......
【讨论】：
引擎不知道super_player 是function，直到您将其声明为一个，因此它没有prototype。
var player = function () {},
super_player = function () {}
// now we can happily set the prototype :)
super_player.prototype = new player();
// don't forget to point the constructor back to super_player
// not doing so will cause great confusion
super_player.prototype.constructor = super_player
【讨论】：
您在第 1 行的注释阻止了结尾括号。所以你有一个悬空的开放式支架，它不起作用。您可以将其更改为以下内容：
var player = function() {
// Declarations here
};
如果我是你，我认为你想考虑使用驼峰式类名来执行以下操作：
function SuperPlayer() {
}
function Player() {
}
Player.prototype = new SuperPlayer();
Player.prototype.constructor = SuperPlayer;
这将使 SuperPlayer 成为基类，而 Player 成为派生类，因为 Player 通过它的原型从 SuperPlayer 继承。不像你在上面的例子中那样。
【讨论】：
你想说
super_player.prototype.player = function(){ /*Declarations here*/ };
?
【讨论】：
再次查看chubbards的答案...原型关键字可以最好地描述为笨拙...这很奇怪，因为它肯定是OOP，但实现很疯狂！
举个常见的例子……
mammal() = object;
cat() = prototype; // Implements mammal();
tiger() = object; // Implements cat(), but does NOT require the 'prototype' keyword... like some kind of 'cystalline' form? I can then create a whole range of individual 'tigers', but will not be able to add any new properties to any of them...
这个怎么样？：
machine() = object;
car() = prototype; // Implements machine. It's a machine afterall...
super_car = prototype; // It's a very fast car...
ferrari = prototype; // They only make supercars...
ferrari_355 = object; // One of the best cars they've ever made. No need to change it, right? :}
对吗？ :|
【讨论】：
非常尊重你 Chubbard。 :)
你的例子很有帮助。
我最初的“示例”相当轻率。 :P
不过，我仍然遇到了一些问题...... 详细说明我的“猫”样本（尽可能简短）：
function mammal(){
// 'mammals' constructor - My 'empirical' 'class'...
}
mammal.count = 0; // To keep track of the zoo I've created. No subclass can access this property. It's a 'static' property
// I could have declared this 'method' inside of my constructor
// with an anonymous function attached to (this.prototype.breathe).
mammal.track = function (){
this.count++;
}
mammal.prototype.breathe = function(){
alert("Inhale... Exhale...");
}
function cat(){
// 'cat' constructor
}
// All cats shall now become a type of mammal
cat.prototype = new mammal();
cat.prototype = function(){
// This anonymous function is the REAL constructor for my 'cat' 'superclass'
}
cat.prototype.meow = function(){
alert("Meow!");
}
function lion(){
// The king of jungle...
// I can keep track of the number of 'mammal' instances I create here
mammal.track();
}
// All lions are cats, afterall...
lion.prototype = new cat();
// Also note that I have no plans to extend the lion class.
// I have no need of a class below the 'idea' of a lion
lion.name = "Kitty"; // :}
// Here's where I get confused...
// I can set (lion.name) via instances, can't call (lion.pounce), but (lion.prototype.roar) works all day long! o_0
lion.pounce = function(){
alert(this.name+" pounces...")
}
lion.prototype.roar = function(){
alert(this.name+" doesn't meow, he ROOOAAARS!");
}
// With these constructs in place, I can now script...
$(document).ready(function(){
var rory = new lion();
var napoleon = new lion();
alert("We have "+mammal.count+" mammals running about");
// This is 'Rory'...
rory.name = 'Rory'; // Respect the pun...
rory.roar();
// This is 'Napoleon'...
napoleon.name = 'Napoleon';
napoleon.breathe(); // Napoleon can't breathe... he didn't inherit mammal.prototype.breathe(), for some reason
napoleon.roar(); // How am I able to set (lion.name), but not call lion.pounce()?
napoleon.pounce();
});
您当然是对的，直到创建最终实例为止，我的链中的每个类都是原型函数。但是为什么 (lion.name) 有效但 (lion.prototype.name) 无效。相反，为什么 lion.prototype.pounce() 可以工作，而 lion.pounce() 失败了？
拿破仑和罗里毕竟都是狮子……
我有很多 Javascript 问题...这是一种非常奇怪的语言... ;)
【讨论】：