JS--定义对象的几种方法

    xiaoxiao2021-12-14  19

    1. 基于已有对象扩充其对象和方法(只适合于临时的生成一个对象):

      var obj = new Object();

      obj.name="userObject";

      obj.printName = function(name){

      this.name = name;

      alert(this.name);

      }

      obj.printName("newUserObject");

      2.工厂方式创建对象(每次创建一个object后,其中对应的方法(本例中是get)也被创建一次,方法不能被所创建的所有对象(本例中是obj1和obj2)共享):

      a.

      function createObject(){

      var obj = new Object();

      obj.name="userObject";

      obj.password = "12345";

      obj.get = function(){

      alert(this.name + ", " + this.password);

      }

      return obj;

      }

      var obj1 = createObject();

      var obj2 = createObject();

      obj1.get();

      obj2.get();

      b.带参数的构造方法:

      function createObject(username,password){

      var obj = new Object();

      obj.username = username;

      obj.password = password;

      obj.get = function(){

      alert(this.username + ", " + this.password);

      }

      return obj;

      }

      var obj1 = createObject("zhangsan","123456");

      obj1.get();

      c.让函数被多个创建的对象所共享,而不是每一个对象都创建一个相同的函数(缺点:对象定义本身和方法分离了):

      function get(){

      alert(this.username + ", " + this.password);

      }

      function createObject(username,password){

      var obj = new Object();

      obj.username = username;

      obj.password = password;

      obj.get = get;

      return obj;

      }

      var obj1 = createObject("zhangsan","123456");

      var obj2 = createObject("lisi","54321");

      obj1.get();

      obj2.get();

      3.构造函数方式:

      a.

      function Person(){

      this.username = "zhangsan";

      this.password = "123";

      this.getInfo = function(){

      alert(this.username + ", " + this.password);

      }

      }

      var person = new Person();

      person.getInfo();

      b.可以在构造函数是传递参数:

      function Person(username,password){

      this.username = username;

      this.password = password;

      this.getInfo = function(){

      alert(this.username + ", " + this.password);

      }

      }

      var person = new Person("zhangsan","123");

      person.getInfo();

      4.使用原型(prototype)方式创建对象:

      优点:创建的多个对象共享同一个方法(getInfo)

      缺点:创建的多个对象在共享同一个方法的同时也共享了同样的属性(username,password),实际开发中这样儿是

      不行的,必须是多个对象都要有自己的属性。

      采用该方式创建对象通常是用来扩展已有对象的某一个方法。

      a.

      function Person(){}

      Person.prototype.username = "zhangsan";

      Person.prototype.password = "123";

      Person.prototype.getInfo = function(){

      alert(this.username + ", " + this.password);

      }

      var person = new Person();

      var person2 = new Person();

      person.username = "lisi";

      person.getInfo();

      person2.getInfo();

      b.如果使用原型方式创建对象,那么生成的所有对象将会共享原型中的属性,这样儿一个对象改变了该属性也会反应到其他的对象上:

      function Person(){}

      Person.prototype.username = new Array(0;

      Person.prototype.password = "123";

      Person.prototype.getInfo = function(){

      alert(this.username + ", " + this.password);

      }

      var person = new Person();

      var person2 = new Person();

      person.username.push("zhangsan");

      person.username.push("lisi");

      person.password = "456";

      person.getInfo();

      person2.getInfo();

      c.使用原型和构造函数方式来创建对象:

      function Person(){

      this.username = new Array();

      this.password = "123"

      }

      Person.prototype.getInfo = function(){

      alert(this.username + ", " + this.password);

      }

      var person = new Person();

      var person2 = new Person();

      person.username.push("zhangsan");

      person.username.push("lisi");

      person.getInfo();

      person2.getInfo();

      5.动态原型方式:在构造函数中通过标志量让所有对象共享一个方法,而每个对象拥有自己的属性。

      function Persion(){

      this.username = "zhangsan";

      this.password = "123";

      if(typeof Person.flag == "undefined"){

      Person.prototype.getInfo = function(){

      alert(this.username + ", " + this.password);

      }

      Person.flag = true;

      }

      }

      var p = new Person();

      var p2 = new Person();

      p.getInfo();

      p2.getInfo();

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