Class Inheritance Advanced

Multilevel Inheritance

A class can inherit a class that inherits other class. A long chain can be formed.

Each child in the chain inherits functions from the ones before it (it's parents grandparents etc...).

Here's an example:

class A { printA() { console.log(this.a); } } class B extends A { printB() { console.log(this.b); } } class C extends B { printC() { console.log(this.c); } } class D extends C { printD() { console.log(this.d); } constructor(aValue, bValue, cValue, dValue) { super(); this.a = aValue; this.b = bValue; this.c = cValue; this.d = dValue; } } let object = new D("AValue", "BValue", "CValue", "DValue"); object.printA(); object.printB(); object.printC(); object.printD();

Output:

AValue BValue CValue DValue

Explanation:

• There is an inheritance chain: A is inherited by B. B is inherited by C. C is inherited by D.
• At line 7 class B inherits class A.
• At line 14 class C inherits class B. Class C inherits the members from B and A. So class C has members - a, b and c.
• At line 21 class D extends class C. Class D is at the bottom of the inherit chain. So it all functions from A, B and C. Class D has functions printA, printB, printC and printD