這篇文章主要介紹了深入理解JavaScript繼承的多種方式和優缺點，具有一定的參考價值，有興趣的小伙伴們可以參考一下
寫在前面
本文講解JavaScript各種繼承方式和優缺點。
注意：
跟《JavaScript深入之建立物件》一樣，更像是筆記。
哎，再讓我感嘆一句：《JavaScript高級程式設計》寫得真是太好了！
1.原型鏈繼承
function Parent () {
this.name = 'kevin';
}
Parent.prototype.getName = function () {
console.log(this.name);
}
function Child () {
}
Child.prototype = new Parent();
var child1 = new Child();
console.log(child1.getName()) // kevin問題：
function Parent () {
this.names = ['kevin', 'daisy'];
}
function Child () {
}
Child.prototype = new Parent();
var child1 = new Child();
child1.names.push('yayu');
console.log(child1.names); // ["kevin", "daisy", "yayu"]
var child2 = new Child();
console.log(child2.names); // ["kevin", "daisy", "yayu"]2.在建立Child 的實例時，不能向Parent傳參
##2.借用建構子(經典繼承)
function Parent () {
this.names = ['kevin', 'daisy'];
}
function Child () {
Parent.call(this);
}
var child1 = new Child();
child1.names.push('yayu');
console.log(child1.names); // ["kevin", "daisy", "yayu"]
var child2 = new Child();
console.log(child2.names); // ["kevin", "daisy"]優點：
1.避免了參考類型的屬性被所有實例共用2.可以在Child 中向Parent 傳參舉例：function Parent (name) {
this.name = name;
}
function Child (name) {
Parent.call(this, name);
}
var child1 = new Child('kevin');
console.log(child1.name); // kevin
var child2 = new Child('daisy');
console.log(child2.name); // daisy3.組合繼承
function Parent (name) {
this.name = name;
this.colors = ['red', 'blue', 'green'];
}
Parent.prototype.getName = function () {
console.log(this.name)
}
function Child (name, age) {
Parent.call(this, name);
this.age = age;
}
Child.prototype = new Parent();
var child1 = new Child('kevin', '18');
child1.colors.push('black');
console.log(child1.name); // kevin
console.log(child1.age); // 18
console.log(child1.colors); // ["red", "blue", "green", "black"]
var child2 = new Child('daisy', '20');
console.log(child2.name); // daisy
console.log(child2.age); // 20
console.log(child2.colors); // ["red", "blue", "green"]4.原型式繼承
function createObj(o) {
function F(){}
F.prototype = o;
return new F();
}Object.create 的模擬實現，將傳入的物件作為創建的物件的原型。
缺點：包含引用類型的屬性值總是會共用對應的值，這點就跟原型鏈繼承一樣。var person = {
name: 'kevin',
friends: ['daisy', 'kelly']
}
var person1 = createObj(person);
var person2 = createObj(person);
person1.name = 'person1';
console.log(person2.name); // kevin
person1.firends.push('taylor');
console.log(person2.friends); // ["daisy", "kelly", "taylor"]person1.name的值，person2.name的值並未改變，並不是因為person1和person2有獨立的name 值，而是因為person1.name = 'person1'，給person1增加了name 值，並非修改了原型上的name 值。
5. 寄生式繼承
function createObj (o) {
var clone = object.create(o);
clone.sayName = function () {
console.log('hi');
}
return clone;
}6. 寄生組合式繼承
function Parent (name) {
this.name = name;
this.colors = ['red', 'blue', 'green'];
}
Parent.prototype.getName = function () {
console.log(this.name)
}
function Child (name, age) {
Parent.call(this, name);
this.age = age;
}
Child.prototype = new Parent();
var child1 = new Child('kevin', '18');
console.log(child1)Child.prototype = new Parent();
var child1 = new Child('kevin', '18');
Parent.call(this, name);
function Parent (name) {
this.name = name;
this.colors = ['red', 'blue', 'green'];
}
Parent.prototype.getName = function () {
console.log(this.name)
}
function Child (name, age) {
Parent.call(this, name);
this.age = age;
}
// 关键的三步
var F = function () {};
F.prototype = Parent.prototype;
Child.prototype = new F();
var child1 = new Child('kevin', '18');
console.log(child1);function object(o) {
function F() {}
F.prototype = o;
return new F();
}
function prototype(child, parent) {
var prototype = object(parent.prototype);
prototype.constructor = child;
child.prototype = prototype;
}
// 当我们使用的时候：
prototype(Child, Parent);以上是js各種繼承方式與優缺點的介紹的詳細內容。更多資訊請關注PHP中文網其他相關文章！
