1.工厂方法
demo.js
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function createPerson(name, age) {
var person = new Object();
person.name = name;
person.age = age;
person.sayHi = function() {
return "name: " + this.name + " age: " + this.age;
};
return person;
}
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优点：创建相同实例只有一处代码。
缺点：不知道对象原型。
test.js
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var person1 = createPerson("zhang", 20);
var person2 = createPerson("li", 30);
console.log(person1.sayHi());
console.log(person2.sayHi());
console.log(person1 instanceof Person); //false
console.log(person2 instanceof Person); //false
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2.构造函数
demo.js
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function Person(name, age) {
this.name = name;
this.age = age;
this.sayHi = function() {
return "name: " + this.name + " age:" + this.age;
};
}
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优点：可以知道实例原型。
缺点：方法不是同一个方法实例。
test.js
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var person1 = new Person("zhang", 20);
var person2 = new Person("li", 30);
console.log(person1.sayHi()); //name: zhang age:20
console.log(person2.sayHi()); //name: li age:30
console.log(person1 instanceof Person); //true
console.log(person2 instanceof Person); //true
console.log(person1.sayHi == person2.sayHi); //false
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3.原型方法
demo.js
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function Person() {}
Person.prototype.name = "zhang";
Person.prototype.age = 20;
Person.prototype.sayHi = function() {
return "name: " + this.name + " age: " + this.age;
};
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优点：共享方法实例对象。
缺点：每个实例需要定义非方法属性。
test.js
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var person1 = new Person();
var person2 = new Person();
person2.name = "li";
person2.age = 30;
console.log(person1.sayHi()); //name: zhang age:20
console.log(person2.sayHi()); //name: li age:30
console.log(person1 instanceof Person); //true
console.log(person2 instanceof Person); //true
console.log(person1.sayHi == person2.sayHi); //true
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4.构造函数和原型的组合方法
demo.js
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function Person(name, age) {
this.name = name;
this.age = age;
}
Person.prototype.sayHi = function() {
return "name: " + this.name + " age: " + this.age;
};
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优点：非方法属性在构造函数中定义，方法属性则在原型中定义。
总结：最后一种方法是比较好的创建对象的方式，综合了前面3种方式的优点。每个实例对象都有自己实例属性的一份副本，但同时共享着方法的引用，最大限度节省了内存。