javascript建構函式繼承

標籤：利用   oop   定義   class   cto   屬性   alt   chinese   包括   

一.傳統prototy繼承

function Parent() {    this.name = "thisIsName";}Parent.prototype.sayName = function() {    return this.name;};function Child() {    this.age = "thisIsAge";}Child.prototype = new Parent();/指向Parent執行個體（包括執行個體的屬性和原型）Child.prototype.constructor = Child;Child.prototype.sayAge = function() {    return this.age;};var c = new Child();console.log(c.name);console.log(c.age);console.log(c.sayName());console.log(c.sayAge());

 

二.利用對象空間繼承

建立一個新的建構函式F，為空白對象，幾乎不佔記憶體

function Chinese() {}Chinese.prototype.nationality = "Chinese";
function Person(name, age) {    this.name = name;    this.age = age;}
function F(){}; //Null 物件幾乎不佔用記憶體F.prototype = Chinese.prototype; //指向同一個原型，互相影響Person.prototype = new F();//new後地址指向F.prototype，F.proptotype也是一個指向原型的地址，故操作Person.prototype不會影響到父類的原型Person.prototype.constructor = Person;Person.prototype.sayName = function() { //Person的prototype中的方法和屬性需要在繼承之後定義    console.log(this.name);};
var p1 = new Person("Oli", 18);console.log(p1.nationality); //Chinesep1.sayName(); //Oli

 

若想繼承非原型上的屬性可增加Chiness.call(this);

function Chinese() {    this.hhh = ‘hhh‘;//新增!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!    this.hello = ‘hello‘;//新增!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1}Chinese.prototype.nationality = "Chinese";function Person(name, age) {    Chinese.call(this);//新增!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!    this.name = name;    this.age = age;}function F(){}; //Null 物件幾乎不佔用記憶體F.prototype = Chinese.prototype; //指向同一個原型，互相影響Person.prototype = new F();//new後地址指向F.prototype，F.proptotype也是一個指向原型的地址，故操作Person.prototype不會影響到父類的原型Person.prototype.constructor = Person;Person.prototype.sayName = function() { //Person的prototype中的方法和屬性需要在繼承之後定義    console.log(this.name);};var p1 = new Person("Oli", 18);console.log(p1.nationality); //Chinesep1.sayName(); //Oliconsole.log(p1.hhh);//新增！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！console.log(p1.hello);//新增！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！

 

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javascript建構函式繼承