How do you extend classes
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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,
class ChildClass extends ParentClass { … }
Let’s take an example of Square subclass from Polygon parent class,
class Square extends Rectangle {
constructor(length) {
super(length, length);
this.name = “Square”;
}
get area() {
return this.width * this.height;
}
set area(value) {
this.area = value;
}
}
The extends keyword is used in class declarations or expressions to create a class that acts as a subclass of another, with the parent class (sometimes called the “base class”) serving as the prototype of the child class (sometimes called the “subclass” or “derived class”).