Question

How to use class interface in TypeScript

Answer 1

interface IPerson {
    iName: string;
    display():void;
    //getSalary(): void;
}

class Employee implements IPerson {
    eID: number;
    iName: string;
    
    constructor(ID: number, name: string) {
        this.eID = ID;
        this.iName = name;
    }
    
    display = () => console.log(this.eID + ' ' + this.iName)

    getSalary() : number {
        return 19250;
    }
}

let per:IPerson = new Employee(857421, 'Professor Albus Dumbledore');

per.display();

// console.log(per.getSalary()); // Property 'getSalary' does not exist on type 'IPerson'.(2339)
    
 

    
/*
    
run:
    
"857421 Professor Albus Dumbledore"
   
*/

 

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Answer 2

interface IPerson {
    iName: string;
    display():void;
    getSalary(): void;
}

class Employee implements IPerson {
    eID: number;
    iName: string;
    
    constructor(ID: number, name: string) {
        this.eID = ID;
        this.iName = name;
    }
    
    display = () => console.log(this.eID + ' ' + this.iName)

    getSalary() : number {
        return 19250;
    }
}

let per:IPerson = new Employee(857421, 'Professor Albus Dumbledore');

per.display();

console.log(per.getSalary()); 
    
 

    
/*
    
run:
    
"857421 Professor Albus Dumbledore"
19250 
   
*/

 

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