我知道这是可行的:
function Foo() {};
Foo.prototype.talk = function () {
alert('hello~\n');
};
var a = new Foo;
a.talk(); // 'hello~\n'
但如果我想打电话
Foo.talk() // this will not work
Foo.prototype.talk() // this works correctly
我找到了一些制作Foo的方法。谈工作,
Foo。__proto__ = Foo.prototype Foo。talk = Foo.prototype.talk
还有别的办法吗?我不知道这样做是否正确。在JavaScript代码中使用类方法还是静态方法?
当前回答
静态方法调用是直接在类上进行的，不能在类的实例上调用。静态方法经常用于 创建效用函数
非常清晰的描述
直接取自mozilla.org
Foo需要绑定到你的类 然后当你创建一个新实例时，你可以调用myNewInstance.foo() 如果你导入你的类，你可以调用一个静态方法
其他回答
Javascript没有实际的类，而是使用一个原型继承系统，其中对象通过原型链从其他对象“继承”。这最好通过代码本身来解释:
function Foo() {}; // creates a new function object Foo.prototype.talk = function () { console.log('hello~\n'); }; // put a new function (object) on the prototype (object) of the Foo function object var a = new Foo; // When foo is created using the new keyword it automatically has a reference // to the prototype property of the Foo function // We can show this with the following code console.log(Object.getPrototypeOf(a) === Foo.prototype); a.talk(); // 'hello~\n' // When the talk method is invoked it will first look on the object a for the talk method, // when this is not present it will look on the prototype of a (i.e. Foo.prototype) // When you want to call // Foo.talk(); // this will not work because you haven't put the talk() property on the Foo // function object. Rather it is located on the prototype property of Foo. // We could make it work like this: Foo.sayhi = function () { console.log('hello there'); }; Foo.sayhi(); // This works now. However it will not be present on the prototype chain // of objects we create out of Foo
当你尝试调用Foo时。JS尝试通过__proto__搜索函数talk，当然，它找不到。
Foo。__proto__是Function.prototype。
当我面对这样的情况时，我是这样做的:
Logger = {
info: function (message, tag) {
var fullMessage = '';
fullMessage = this._getFormatedMessage(message, tag);
if (loggerEnabled) {
console.log(fullMessage);
}
},
warning: function (message, tag) {
var fullMessage = '';
fullMessage = this._getFormatedMessage(message, tag);
if (loggerEnabled) {
console.warn(fullMessage);`enter code here`
}
},
_getFormatedMessage: function () {}
};
现在我可以调用info方法as Logger.info(“我的Msg”，“标签”);
ES6现在支持类和静态关键字，就像一个魅力:
class Foo {
constructor() {}
talk() {
console.log("i am not static");
}
static saying() {
console.log(this.speech);
}
static get speech() {
return "i am static method";
}
}
下面是一个很好的例子来演示Javascript如何处理静态/实例变量和方法。
function Animal(name) {
Animal.count = Animal.count+1||1;// static variables, use function name "Animal"
this.name = name; //instance variable, using "this"
}
Animal.showCount = function () {//static method
alert(Animal.count)
}
Animal.prototype.showName=function(){//instance method
alert(this.name);
}
var mouse = new Animal("Mickey");
var elephant = new Animal("Haddoop");
Animal.showCount(); // static method, count=2
mouse.showName();//instance method, alert "Mickey"
mouse.showCount();//Error!! mouse.showCount is not a function, which is different from Java
