4.js里面的继承
1.混入式继承(mix-in)
//继承1个对象
var o = {
extend: function(obj){
for(var k in obj){
this[k] = obj[k];
}
}
};
o.extend(o1);
//继承多个对象
var o = {
extend: function(){
for (var i = 0; i < arguments.length; i++) {
var obj = arguments[i];
for(var k in obj){
this[k] = obj[k];
}
}
}
}
o.extend(o1, o2, o3, o4);
2.经典继承(Object.create)
语法:var obj = Object.create(obj1);
含义:创建一个对象obj,并且继承了obj1
不兼容ie8以下
function myCreate (obj){
if (Object.creat) {
return Object.creat(obj)
} else{
function F(){};
F.prototype = obj;
return new F ();
}
}
3.继承的方式也有很多种:原型链继承、借用构造函数继承、组合继承、原型式继承、寄生式继承、寄生组合式继承……
WTF ! 简直要吐血有木有
那就用一种自己最熟练的就好了,形成自己的风格吧!
//组合使用构造函数模式和原型模式 创建对象
//父类
function Person(name){
this.name = name || "Tom";
this.age = "12";
//实例方法 (不会被覆盖)
this.say = function(){
console.log("Hello " + this.name + "!");
}
}
//原型方法
Person.prototype.run = function(){
console.log(this.name + " is running");
}
Person.prototype.eat = function(food){
console.log(this.name + " is eating " + food);
}
/*更方便的写法:
* Person.prototype = { //这里相当于完全重写了默认的prototype对象,constructor属性也变成了新的对象的constructor属性(指向Object)
constructor: Person, //将构造器重新指向Person
run: funtion(){
console.log(this.name + " is running");
},
eat: function(){
console.log(this.name + " is eating " + food);
}
}*/
//组合继承:通过调用父类构造函数,继承父类的属性并保留传参的优点,然后通过将父类实例作为子类原型,实现函数复用
//子类
function People(name){
Person.call(this); //构造函数继承 (调用父类构造函数)
this.name = name || "Rose"; //修改继承的属性
this.sport = "football"; //自定义新的属性
}
People.prototype = new Person(); //原型继承 (将父类实例作为子类原型)
People.prototype.say = function(){ //修改继承的方法
console.log("Hello " + this.name + " you are welcome");
}
People.prototype.run = function(){ //修改继承的方法
console.log(this.name + " is go go go");
}
People.prototype.play = function(){ //自定义新的方法
console.log(this.name + " is playing " + this.sport);
}
//test
var person1 = new People("Jack");
console.log(person1.name); //Jack
console.log(person1.age); //12 //继承原型的属性
person1.say(); //Hello Jack! //实例方法无法在其原型上修改。 如此修改:person1.say(){ balabala }
person1.run(); //Jack is go go go //覆盖了原型方法
person1.eat("apple"); //Jack is eating apple
var person2 = new People("Lucy");
console.log(person2.name); //Lucy
console.log(person2.age); //12 //继承原型的属性
person2.say(); //Hello Lucy! //实例方法无法在其原型上修改
person2.run(); //Lucy is go go go //覆盖了原型方法
person2.eat("apple"); //Lucy is eating apple
person2.play(); //Lucy is playing football
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