Hierarchical Inheritance

Definition

Hierarchical inheritance occurs when multiple child classes inherit from the same parent class. The parent provides shared behavior, and each child adds its own specialization.

Characteristics

Aspect	Description
Structure	One parent → many children
Complexity	Low — children are independent
Reuse	High — shared code in parent
Benefit	Organizes related types under one concept

Example

class Employee {
  constructor(name, id) {
    this.name = name;
    this.id = id;
  }

  work() {
    return `${this.name} is working`;
  }
}

class Developer extends Employee {
  constructor(name, id, language) {
    super(name, id);
    this.language = language;
  }

  work() {
    return `${this.name} is coding in ${this.language}`;
  }
}

class Manager extends Employee {
  constructor(name, id, teamSize) {
    super(name, id);
    this.teamSize = teamSize;
  }

  work() {
    return `${this.name} is managing ${this.teamSize} people`;
  }
}

class Designer extends Employee {
  constructor(name, id, tool) {
    super(name, id);
    this.tool = tool;
  }

  work() {
    return `${this.name} is designing in ${this.tool}`;
  }
}

Visual Diagram

classDiagram
    class Employee {
        +name: string
        +id: int
        +work() string
    }

    class Developer {
        +language: string
        +work() string
    }

    class Manager {
        +teamSize: int
        +work() string
    }

    class Designer {
        +tool: string
        +work() string
    }

    Employee <|-- Developer : extends
    Employee <|-- Manager : extends
    Employee <|-- Designer : extends

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