typescript abstract class member code example

Example 1: ts abstract class

abstract class Person {
    name: string;
    
    constructor(name: string) {
        this.name = name;
    }

    display(): void{
        console.log(this.name);
    }

    abstract find(string): Person;
}

class Employee extends Person { 
    empCode: number;
    
    constructor(name: string, code: number) { 
        super(name); // must call super()
        this.empCode = code;
    }

    find(name:string): Person { 
        // execute AJAX request to find an employee from a db
        return new Employee(name, 1);
    }
}

let emp: Person = new Employee("James", 100);
emp.display(); //James

let emp2: Person = emp.find('Steve');

Example 2: abstract classes in typescript

abstract class Department {
  constructor(public name: string) {}

  printName(): void {
    console.log("Department name: " + this.name);
  }

  abstract printMeeting(): void; // must be implemented in derived classes
}

class AccountingDepartment extends Department {
  constructor() {
    super("Accounting and Auditing"); // constructors in derived classes must call super()
  }

  printMeeting(): void {
    console.log("The Accounting Department meets each Monday at 10am.");
  }

  generateReports(): void {
    console.log("Generating accounting reports...");
  }
}

let department: Department; // ok to create a reference to an abstract type
department = new Department(); // error: cannot create an instance of an abstract class
Cannot create an instance of an abstract class.2511Cannot create an instance of an abstract class.department = new AccountingDepartment(); // ok to create and assign a non-abstract subclass
department.printName();
department.printMeeting();
department.generateReports();
Property 'generateReports' does not exist on type 'Department'.2339Property 'generateReports' does not exist on type 'Department'.Try