JavaScript中的對象導論

面向對象編程（OOP）是一種編碼方法，它將代碼封裝為對象，并通過這些對象之間的交互來完成操作。JavaScript是一種靈活多變，非常適合實現OOP的編程語言。

問題1. 如何創建對象？

//通過對象字面量創建對象
let obj = {
name: 'Alex',
age: 24,
gender: 'Male'
};
//通過構造函數創建對象
function Person(name, age, gender) {
this.name = name;
this.age = age;
this.gender = gender;
}
let person = new Person('Alex', 24, 'Male');
//通過Object.create()方法創建對象
let obj1 = Object.create(null); //創建一個空對象
let obj2 = Object.create(obj); //繼承obj的屬性和方法的對象

問題2. 如何使用prototype繼承？

prototype是JavaScript中用于實現繼承的機制。它可以在子對象中訪問父對象中的屬性和方法。

function Person(name, age, gender) {
this.name = name;
this.age = age;
this.gender = gender;
}
Person.prototype.sayHello = function() {
console.log('Hello, my name is ' + this.name);
}
function Student(name, age, gender, major) {
Person.call(this, name, age, gender);
this.major = major;
}
Student.prototype = Object.create(Person.prototype);
Student.prototype.constructor = Student;
let student = new Student('Alex', 24, 'Male', 'Computer Science');
student.sayHello();

問題3. 什么是封裝？

封裝是一種保護對象屬性和方法不被外部訪問的方法。在JavaScript中使用閉包實現封裝。

function Person(name, age, gender) {
let _name = name;
let _age = age;
let _gender = gender;
this.getName = function() {
return _name;
};
this.getAge = function() {
return _age;
};
this.getGender = function() {
return _gender;
};
this.setName = function(name) {
_name = name;
};
this.setAge = function(age) {
_age = age;
};
this.setGender = function(gender) {
_gender = gender;
};
}

問題4. 如何使用繼承的“多態”特性

多態是面向對象編程中，子類可以覆蓋父類的方法，并賦予不同的實現方式，以達到更靈活的編程目的。

function Person() {}
Person.prototype.sayHello = function() {
console.log('Hello, I am a Person');
}
function Student() {}
Student.prototype = Object.create(Person.prototype);
Student.prototype.constructor = Student;
Student.prototype.sayHello = function() {
console.log('Hello, I am a Student');
}
function Teacher() {}
Teacher.prototype = Object.create(Person.prototype);
Teacher.prototype.constructor = Teacher;
Teacher.prototype.sayHello = function() {
console.log('Hello, I am a Teacher');
}
let person = new Person();
let student = new Student();
let teacher = new Teacher();
person.sayHello();
student.sayHello();
teacher.sayHello();

以上就是JavaScript中面向對象編程的常見問題，希望能夠對你的編程有所啟發。