要创建一个带有公共方法的JavaScript类，我可以这样做:
function Restaurant() {}
Restaurant.prototype.buy_food = function(){
// something here
}
Restaurant.prototype.use_restroom = function(){
// something here
}
这样，我类的用户就可以:
var restaurant = new Restaurant();
restaurant.buy_food();
restaurant.use_restroom();
如何创建一个私有方法，可以由buy_food和use_restroom方法调用，但不能由类的用户外部调用?
换句话说，我希望我的方法实现能够做到:
Restaurant.prototype.use_restroom = function() {
this.private_stuff();
}
但这是行不通的:
var r = new Restaurant();
r.private_stuff();
如何将private_stuff定义为私有方法，使两者都成立?
我读过Doug Crockford的文章几次，但它似乎不像“私有”方法可以被公共方法调用，而“特权”方法可以被外部调用。
以下是迄今为止我最喜欢的关于javascript中的私有/公共方法/成员和实例化:
这是文章:http://www.sefol.com/?p=1090
下面是一个例子:
var Person = (function () {
//Immediately returns an anonymous function which builds our modules
return function (name, location) {
alert("createPerson called with " + name);
var localPrivateVar = name;
var localPublicVar = "A public variable";
var localPublicFunction = function () {
alert("PUBLIC Func called, private var is :" + localPrivateVar)
};
var localPrivateFunction = function () {
alert("PRIVATE Func called ")
};
var setName = function (name) {
localPrivateVar = name;
}
return {
publicVar: localPublicVar,
location: location,
publicFunction: localPublicFunction,
setName: setName
}
}
})();
//Request a Person instance - should print "createPerson called with ben"
var x = Person("ben", "germany");
//Request a Person instance - should print "createPerson called with candide"
var y = Person("candide", "belgium");
//Prints "ben"
x.publicFunction();
//Prints "candide"
y.publicFunction();
//Now call a public function which sets the value of a private variable in the x instance
x.setName("Ben 2");
//Shouldn't have changed this : prints "candide"
y.publicFunction();
//Should have changed this : prints "Ben 2"
x.publicFunction();
JSFiddle: http://jsfiddle.net/northkildonan/kopj3dt3/1/
以下是迄今为止我最喜欢的关于javascript中的私有/公共方法/成员和实例化:
这是文章:http://www.sefol.com/?p=1090
下面是一个例子:
var Person = (function () {
//Immediately returns an anonymous function which builds our modules
return function (name, location) {
alert("createPerson called with " + name);
var localPrivateVar = name;
var localPublicVar = "A public variable";
var localPublicFunction = function () {
alert("PUBLIC Func called, private var is :" + localPrivateVar)
};
var localPrivateFunction = function () {
alert("PRIVATE Func called ")
};
var setName = function (name) {
localPrivateVar = name;
}
return {
publicVar: localPublicVar,
location: location,
publicFunction: localPublicFunction,
setName: setName
}
}
})();
//Request a Person instance - should print "createPerson called with ben"
var x = Person("ben", "germany");
//Request a Person instance - should print "createPerson called with candide"
var y = Person("candide", "belgium");
//Prints "ben"
x.publicFunction();
//Prints "candide"
y.publicFunction();
//Now call a public function which sets the value of a private variable in the x instance
x.setName("Ben 2");
//Shouldn't have changed this : prints "candide"
y.publicFunction();
//Should have changed this : prints "Ben 2"
x.publicFunction();
JSFiddle: http://jsfiddle.net/northkildonan/kopj3dt3/1/
Class({
Namespace:ABC,
Name:"ClassL2",
Bases:[ABC.ClassTop],
Private:{
m_var:2
},
Protected:{
proval:2,
fight:Property(function(){
this.m_var--;
console.log("ClassL2::fight (m_var)" +this.m_var);
},[Property.Type.Virtual])
},
Public:{
Fight:function(){
console.log("ClassL2::Fight (m_var)"+this.m_var);
this.fight();
}
}
});
https://github.com/nooning/JSClass
既然每个人都在这里张贴自己的代码，我也要这样做…
我喜欢Crockford，因为他在Javascript中引入了真正的面向对象模式。但他也产生了一个新的误解，那个“那个”。
那么他为什么要用"that = this"呢?这和私人活动完全没有关系。它与内部函数有关!
因为根据Crockford的说法，这是有bug的代码:
Function Foo( ) {
this.bar = 0;
var foobar=function( ) {
alert(this.bar);
}
}
所以他建议这样做:
Function Foo( ) {
this.bar = 0;
that = this;
var foobar=function( ) {
alert(that.bar);
}
}
就像我说的，我很确定Crockford对这个和这个的解释是错误的(但他的代码肯定是正确的)。或者他只是在愚弄Javascript世界，知道谁在复制他的代码?我不知道……我不是浏览器极客
EDIT
啊，这就是问题所在:'var that = this;'在JavaScript中是什么意思?
所以Crockie的解释是错误的....但他的代码是正确的，所以他还是个好人。:))
老问题，但这是一个相当简单的任务，可以用核心JS正确解决…没有ES6的Class抽象。事实上，据我所知，类抽象甚至不能解决这个问题。
我们既可以使用老的构造函数，也可以使用Object.create()更好地完成这项工作。让我们先从构造函数开始。这本质上是一个与georgebrock的答案相似的解决方案，georgebrock的答案受到了批评，因为所有由Restaurant构造函数创建的餐厅都将具有相同的私有方法。我会努力克服这个限制。
function restaurantFactory(name,menu){
function Restaurant(name){
this.name = name;
}
function prototypeFactory(menu){
// This is a private function
function calculateBill(item){
return menu[item] || 0;
}
// This is the prototype to be
return { constructor: Restaurant
, askBill : function(...items){
var cost = items.reduce((total,item) => total + calculateBill(item) ,0)
return "Thank you for dining at " + this.name + ". Total is: " + cost + "\n"
}
, callWaiter : function(){
return "I have just called the waiter at " + this.name + "\n";
}
}
}
Restaurant.prototype = prototypeFactory(menu);
return new Restaurant(name,menu);
}
var menu = { water: 1
, coke : 2
, beer : 3
, beef : 15
, rice : 2
},
name = "Silver Scooop",
rest = restaurantFactory(name,menu);
console.log(rest.callWaiter());
console.log(rest.askBill("beer", "beef"));
现在显然我们不能从外部访问菜单，但我们可以很容易地重命名餐厅的name属性。
这也可以用object .create()来完成，在这种情况下，我们跳过构造函数，简单地像var rest = object .create(prototypeFactory(menu))那样做，然后像rest.name = name那样将name属性添加到rest对象。
这是我得出的结论:
需要一类糖代码，你可以在这里找到。还支持保护，继承，虚拟，静态的东西…
;( function class_Restaurant( namespace )
{
'use strict';
if( namespace[ "Restaurant" ] ) return // protect against double inclusions
namespace.Restaurant = Restaurant
var Static = TidBits.OoJs.setupClass( namespace, "Restaurant" )
// constructor
//
function Restaurant()
{
this.toilets = 3
this.Private( private_stuff )
return this.Public( buy_food, use_restroom )
}
function private_stuff(){ console.log( "There are", this.toilets, "toilets available") }
function buy_food (){ return "food" }
function use_restroom (){ this.private_stuff() }
})( window )
var chinese = new Restaurant
console.log( chinese.buy_food() ); // output: food
console.log( chinese.use_restroom() ); // output: There are 3 toilets available
console.log( chinese.toilets ); // output: undefined
console.log( chinese.private_stuff() ); // output: undefined
// and throws: TypeError: Object #<Restaurant> has no method 'private_stuff'
