zoukankan      html  css  js  c++  java
  • Javascript Design Patterns

    JavaScript is a class-less language, however classes can be simulated using functions. 

    eg:

    // A car 'class'
    function Car(model) { 
        this.model = model; 
        this.color = 'silver'; 
        this.year = '2012'; 
        this.getInfo = function () {
            return this.model + ' ' + this.year; 
        }
    }

    We can then instantiate the object using the Car constructor we defined above like this: 

    var myCar = new Car('ford'); 
    myCar.year = '2010'; 
    console.log(myCar.getInfo());

    另一个例子

    var Person = function (name) { 
        this.name = name;
        this.say = function () {
            return "I am " + this.name; 
        };
    };
    
    // use the class
    var adam = new Person("Adam"); 
    adam.say(); // "I am Adam"

    上述关于类函数的做法性能不佳,原因如下:

    any time you call new Person() a new function is created in memory.

    This is obviously inefficient, because the say() method doesn’t change from one instance to the next.

    (每次new对象的时候会在内存中新建一个函数)

    The better option is to add the method to the prototype of Person 

    (比较好的方法是把方法增加到Person对象的prototype)

    Person.prototype.say = function () {
        return "I am " + this.name; 
    };

    just remember that reusable members, such as methods, should go to the prototype 

    (关于JS类必须要记住的是,可重用的成员,例如方法必须放到对象的prototype)

  • 相关阅读:
    JS判断对象中是否存在某参数
    JS通过url下载文件
    .NET CORE LinQ查询中计算时间差
    C# 判断某个时间是星期几
    C#数组去重
    python Tank
    kubeflannel.yml Tank
    片言只语 Tank
    other Tank
    ERROR大集合 Tank
  • 原文地址:https://www.cnblogs.com/davidgu/p/3294687.html
Copyright © 2011-2022 走看看