原型繼承

原型繼承是對類式繼承的一種封裝，其中的過渡物件就相當於類式繼承中的子類，只是在原型式中作為一個過渡物件出現，目的是建立要返回的新的例項化物件。和類式繼承一樣，父類物件book中指型別的屬性被複制，引用型別的屬性被共有。

//原型是繼承
function inheritObject(o) {
//宣告一個過渡函式物件
function F(){}
//過渡物件的原型繼承父類
F.prototype = o;
//返回過渡物件的一個例項，該例項的原型繼承了父物件
return new F();
}

var book ={
name:"js",
alikeBook:["css","html"]
};
//測試程式碼
var newBook = inheritObject(book);
newBook.name ="ajax";
newBook.alikeBook.push("new xml book");
var otherBook = inheritObject(book);
otherBook.name ="flash";
otherBook.alikeBook.push("other as book");
console.log(newBook.name);//ajax
console.log(newBook.alikeBook);//[ 'css', 'html', 'new xml book', 'other as book' ]
console.log(otherBook.name);//flash
console.log(otherBook.alikeBook);//[ 'css', 'html', 'new xml book', 'other as book' ]
console.log(book.name);//js
console.log(book.alikeBook);//[ 'css', 'html', 'new xml book', 'other as book' ]
 

寄生式繼承

寄生式繼承是對原型繼承的第二次封裝，並且在封裝的過程中對繼承物件進行了擴充套件，這樣新建立的物件不僅僅有父類中的屬性和方法，而且添加了新的屬性和方法。

//寄生式繼承var newBook = createBook(book);newBook.name = "js";newBook.alikeBook.push("new");var otherBook = createBook(book);otherBook.name = "bad";otherBook.alikeBook.push("other");
//宣告基物件
var book = {
name:'js book',
alikeBook: ["css","html"]
};
function createBook(obj) {
//通過原型繼承方式建立新物件
var o = new inheritObject(obj);
o.getName = function () {
console.log(name);
}
//返回拓展後的新物件
return o;
}
//測試程式碼
var newBook = createBook(book);
newBook.name = "js";
newBook.alikeBook.push("new");
var otherBook = createBook(book);
otherBook.name = "bad";
otherBook.alikeBook.push("other");
console.log(newBook.name);//ajax
console.log(newBook.alikeBook);//[ 'css', 'html', 'new xml book', 'other as book' ]
console.log(otherBook.name);//flash
console.log(otherBook.alikeBook);//[ 'css', 'html', 'new xml book', 'other as book' ]
console.log(book.name);//js
console.log(book.alikeBook);//[ 'css', 'html', 'new xml book', 'other as book' ]