类和对象�_�>

类和对象用于创建和使用可重用的代码。类是创建对象的蓝图，对象是类的特定实例。�_p> <16�p class="anchor anchorWithHideOnScrollNavbar_WYt5" id="任务">任务

创建一个 Circle 的类，该类可以计算圆的面积和周长。�_p>

class�_span>Circle {�_span>
�_span>  �_span>static pi �_span>=�_span>.PI�_span>
�_span>  �_span>constructor�_span>(radius�_span>) {�_span>
�_span>    �_span>this.�_span>radius �_span>=�_span>;�_span>
}�_span>
�_span>
�_span>  �_span>static createCircle�_span>(radius�_span>){�_span>
�_span>    �_span>return new Circle�_span>(radius�_span>)�_span>
}�_span>
�_span>
�_span>  �_span>getArea�_span>()�_span>{�_span>
return�_span>.pi * this�_span>.radius **�_span>;�_span>
}�_span>
�_span>
�_span>  �_span>getCircumference(�_span>) {�_span>
�_span>    �_span>return 2 * Circle.�_span>pi �_span>*�_span>this.�_span>radius;�_span>
�_span>  �_span>}�_span>
�_span>
toString�_span>()�_span>{�_span>
return�_span>`[Circle]: radius:${this�_span>.radius�_span>}`�_span>
�_span>  �_span>}�_span>
}�_span>
�_span>
�_span>�_span>const�_span>= new Circle�_span>(5)�_span>; 
�_span>�_span>console.�_span>log�_span>(circle�_span>.toString�_span>()�_span>);�_span>�] [Circle]: radius:5�_span>
console�_span>.log(�_span>circle.�_span>getArea�_span>()�_span>);�_span>�] 78.�0�0�09816�0�0�0�09744�0�0�0�_span>
�_span>�_span>console.�_span>log�_span>(circle�_span>.getCircumference�_span>()�_span>);�_span>�]�0�0�0�0�01.5926�0�0�05897�0�0�0�_span>
�_code>

�_div>�_div>�_div>

class 中的 static 关键字原来是 TypeScript 提供的特性，但�)ES20(	g) 起已经�RsJavaScript 中原生支持了�2除此之外，TypeScrip4还提供了 public、private�_code>、protected 访问修饰符。


Python 实现
import�_span>
�_span>
class Circle�_span>:�_span>
=�_span>.pi�_span>
def __init__�_span>(self�_span>, radius)�_span>:�_span>
.�_span>radius �_span>=�_span>
�_span>
@classmethod�_span>
�_span>  �_span>def�_span>create_circle�_span>(cls,�_span>radius)�_span>:�_span>
return�_span>(radius�_span>)�_span>

�_span>  �_span>def�_span>get_area(�_span>self)�_span>:�_span>
return�_span>.pi * self.�_span>radius �_span>** 2�_span>
�_span>
def get_circumference(�_span>self)�_span>:�_span>
return�_span>*�_span>.pi * self.�_span>radius
�_span>
�_span>  �_span>def�_span>__str__�_span>(self�_span>):�_span>
�_span>    �_span>return f"[Circle] radius:�_span>{�_span>self�_span>.�_span>radius�_span>}�_span>"�_span>
�_span>
�_span>circle = Circle(�_span>5�_span>) # 或 Circle.create_circle(5)�_span>
�_span>�_span>print�_span>(circle�_span>) # [Circle] radius:5�_span>
�_span>�_span>print�_span>(circle�_span>.get_area�_span>()�_span>) # 78.�0�0�09816�0�0�0�09744�0�0�0�_span>
�_span>�_span>print�_span>(circle�_span>.get_circumference(�_span>))�_span># �.415(�N)653589793
�_span>�_pre>

特性	JavaScript�_th>	Python
定义类	`class ClassName {}�_code>`	`class ClassName:�_code>`
创建对象	`le4myObj = ne7ClassName();�_code>`	`my_obj = ClassName()�_code>`
构造函数	`constructor() {}�_code>`	`def __init__(self):`�_td>
类属性赋值	`this.propertyName = value;�_code>`	`self.propertyName = value`�_td>
类方法	`methodName() {}`�_td>	`def methodName(self):�_code>`
继承	`class ChildClass extends ParentClass {}`�_td>	`class ChildClass(ParentClass):`�_td>
对象销毁�_td>	无内置支持�_td>	`def __del__(self):`�_td>

Python 实现​

Python 实现