面向对象的JavaScript系列一,创建对象
1.最简单的创建对象方法
var person = new Object(); person.name = "sam wu"; person.age = 25; person.job = "frontend engineer"; person.sayName = function(){ alert(this.name); }; person.sayName();
2.工厂模式创建对象
function createPerson(name, age, job){ var o = new Object(); o.name = name; o.age = age; o.job = job; o.sayName = function(){ alert(this.name); }; return o; } var person1 = createPerson("sam", 29, "frontend Engineer"); var person2 = createPerson("rendy", 27, "Python"); person1.sayName(); //"sam" person2.sayName(); //"rendy"
3.构造函数模式
function Person(name, age, job){ this.name = name; this.age = age; this.job = job; this.sayName = function(){ alert(this.name); }; } var person1 = new Person("sam", 29, "frontend Engineer"); var person2 = new Person("rendy", 27, "Python"); person1.sayName(); //"sam" person2.sayName(); //"rendy" alert(person1 instanceof Object); //true alert(person1 instanceof Person); //true alert(person2 instanceof Object); //true alert(person2 instanceof Person); //true alert(person1.constructor == Person); //true alert(person2.constructor == Person); //true alert(person1.sayName == person2.sayName); //false
4.原型模式
可以让多个实例,共享属性和方法。
function Person(){ } Person.prototype.name = "sam"; Person.prototype.age = 25; Person.prototype.job = "Software Engineer"; Person.prototype.sayName = function(){ alert(this.name); }; var person1 = new Person(); person1.sayName(); //"sam" var person2 = new Person(); person2.sayName(); //"sam" alert(person1.sayName == person2.sayName); //true alert(Person.prototype.isPrototypeOf(person1)); //true alert(Person.prototype.isPrototypeOf(person2)); //true //only works if Object.getPrototypeOf() is available.ECMA5支持 if (Object.getPrototypeOf){ alert(Object.getPrototypeOf(person1) == Person.prototype); //true alert(Object.getPrototypeOf(person1).name); //"sam" }
4.1 实例对象属性和原型属性的优先级
function Person(){ } Person.prototype.name = "sam"; Person.prototype.age = 29; Person.prototype.job = "Software Engineer"; Person.prototype.sayName = function(){ alert(this.name); }; var person1 = new Person(); var person2 = new Person(); person1.name = "Rendy"; alert(person1.name); //"Rendy" – from instance 来自对象 alert(person2.name); //"sam" – from prototype 来自原型属性
4.2 同名,只是屏蔽,非覆盖
function Person(){ } Person.prototype.name = "sam"; Person.prototype.age = 29; Person.prototype.job = "Software Engineer"; Person.prototype.sayName = function(){ alert(this.name); }; var person1 = new Person(); var person2 = new Person(); person1.name = "rendy"; alert(person1.name); //"rendy" – from instance alert(person2.name); //"sam" – from prototype delete person1.name; alert(person1.name); //"sam" - from the prototype
5.组合使用构造函数模式和原型模式
function Person(name, age, job){ this.name = name; this.age = age; this.job = job; this.friends = ["Shelby", "Court"]; } Person.prototype = { constructor: Person, sayName : function () { alert(this.name); } }; var person1 = new Person("sam", 29, "Frontend Engineer"); var person2 = new Person("rendy", 27, "Python"); person1.friends.push("christ"); alert(person1.friends); //"Shelby,Court,christ" alert(person2.friends); //"Shelby,Court" alert(person1.friends === person2.friends); //false alert(person1.sayName === person2.sayName); //true
6.寄生构造函数函数模式
function Person(name, age, job){ var o = new Object(); o.name = name; o.age = age; o.job = job; o.sayName = function(){ alert(this.name); }; return o; } // 这里用了new关键字,但是Person函数的内容是返回一个对象。这样就不会生成一个新的实例。而是跟工厂模式效果一样。 var friend = new Person("sam", 25, "Front Engineer"); friend.sayName(); //"sam"
以上内容来自《JavaScript高级程序设计第三版》
合乎自然而生生不息。。。