Javascript继承静态和实例方法/属性

Javascript inherit static and instance methods/properties

本文关键字：属性 实例方法 继承 静态 Javascript      更新时间：2023-09-26

在javascript中，我如何设置继承，使静态和实例属性/方法被继承?

我的目标是建立一个基"类"，第三方可以继承，并能够调用从基"类"继承的静态和实例属性/方法。

在我的例子中，我定义了一个食谱基类，其他人可以继承并创建食谱:

Function.prototype.inherits = function (base) {
  // code to inherit instance and static
  // props/methods here
  var temp = function () { };
  temp.prototype = base.prototype;
  this.prototype = new temp();
}
function Recipe() {
  var self = this;
  Recipe.ingredients = { };
  Recipe.prepare = function (ingredients) {
    // prepare each of the ingredients...
    var preparedIngredients = ingredients;
    Recipe.ingredients = preparedIngredients;
  };
  self.share = function () {
    console.log('Recipe Shared!');
  };
}
Toast.inherits(Recipe);
function Toast() {
  var self = this;
}
var toast = new Toast();
// Child function should inherit static methods
Toast.Prepare({
  bread: '2 slices',
  butter: '1 knob',
  jam: '1 tablespoon'
});
// Child function should inherit static properties
console.log(Toast.ingredients);
// Child function should inherit instance methods as well
toast.share();
// And if I define another it gets its own static properties/methods
// Spaghetti.ingredients !== Toast.ingredients
Spaghetti.inherits(Recipe);
function Spaghetti() {
  var self = this;
}
Spaghetti.prepare({
  noodles: '1 box',
  tomatoes: 2,
  sausage: 1
});

Plnkr here: http://plnkr.co/edit/x8rKeKXSxDHMB4CD6j1c

你的继承是错误的，Toast不是一个Recipe它有一个Recipe。Recipe的配料不能是静态的，因为Recipe可以用于烤面包、煎饼或许多其他菜肴。

function Recipe(name,ingredients) {
  this.name=name;
  this.ingredients = ingredients;
};
var Toast = function(){}
Toast.prototype.recipe = new Recipe('toast',{
  bread: '2 slices',
  butter: '1 knob',
  jam: '1 tablespoon'
});

关于原型的更多信息可以在这里找到:https://stackoverflow.com/a/16063711/1641941

如果你想继承静态成员，你需要一个更好的例子:例如MyDate和MyDateTime。

var MyDate=function(dateString){
  this.date=(dateString)?new Date(dateString)
    :new Date();
};
MyDate.YEAR=Date.prototype.getFullYear;
//... others like MONTH, DAY ...
MyDate.prototype.get = function(what){
  if(what && typeof what==='function'){
      return what.call(this.date);
  }
  console.log('nope');
};
var MyDateTime=function(dateString){
  MyDate.call(this,dateString);
};
//set static properties (can write a function for this)
for(mystatic in MyDate){
  if(MyDate.hasOwnProperty(mystatic)){
    MyDateTime[mystatic]=MyDate[mystatic];
  }
}
MyDateTime.HOUR=Date.prototype.getHours;
//instead of breaking encapsulation for inheritance
// maybe just use Object.create and polyfil if needed
// and stop reading DC when it comes to this subject
MyDateTime.prototype=Object.create(MyDate.prototype);
MyDateTime.prototype.constructor=MyDateTime;
var d = new MyDate();
console.log(d.get(MyDate.YEAR));
var dt = new MyDateTime();
console.log(dt.get(MyDateTime.YEAR));
console.log(dt.get(MyDateTime.HOUR));

这是一个静态/实例成员继承的例子。这是使用我编写的小类框架，使javascript中的oop更容易使用和更好看。如果你感兴趣，可以在github上找到。

var Base = new ds.class({
    type: 'Base',
    constructor: function() {
        this.instanceprop: 'am i instance?'
    },
    staticprop: 'am i static?'
});
var Example = new ds.class({
    type: 'Example',
    inherits: Base,
    constructor: function() {}
});
var eb = new Base();
var ex = new Example();
console.log( Base.staticprop );
console.log( eb.instanceprop );
console.log( Example.staticprop );
console.log( ex.instanceprop );
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