Creating "new" objects on Node.Js

This question already has an answer here:

What is the 'new' keyword in JavaScript? 13 answers

---

Take this for example:

function SomeClass() {}
SomeClass.prototype = {
    sayHi: function() {
        console.log('hello');
    }
};

function foo() {
    return new SomeClass();
}

foo() // => returns a new SomeClass object

In that case, foo is what they're referring to as a "factory" function, in that it is sort of like a type of factory that creates objects (just like in real life how factories create new objects; car factories, etc.)

It's also good for singletons:

(function() {
    var singleton;

    function SomeClass() {}
    SomeClass.prototype = {
        sayHi: function() {
            console.log('hello');
        }
    };

    function foo() {
        singleton = singleton || new SomeClass();
        return singleton;
    }

    window.foo = foo;
}());

foo(); // returns a new SomeClass
foo(); // returns the same SomeClass instance (not a new one). This is a singleton.

Node.js is just regular JavaScript, so in the example you've given, all you're doing is including the factory from a module and using it to create new objects (instances of "classes").

---

如果不使用新关键字，则可能表示它们在需要时返回新对象。

链接地址: http://www.djcxy.com/p/40868.html

上一篇: 了解“this”关键字的范围

下一篇: 在Node.Js上创建“新”对象