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The extends keyword is used in class declarations/expressions to create a class which is a child of another class. It can be used to subclass custom classes as well as built-in objects. The syntax would be as below,
javascript
1class ChildClass extends ParentClass { ... }Let's take an example of Square subclass from Polygon parent class,
javascript
1class Square extends Rectangle {
2 constructor(length) {
3 super(length, length);
4 this.name = "Square";
5 }
6
7 get area() {
8 return this.width * this.height;
9 }
10
11 set area(value) {
12 this.area = value;
13 }
14 }Advertisement
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