declare interface typescript code example

Example 1: typescript interface function

interface IEmployee {
    empCode: number;
    empName: string;
    getSalary: (number) => number; // arrow function
    getManagerName(number): string; 
}

Example 2: typescript class interface

interface IPerson {
  name: string
  age: number
  hobby?: string[]
}

class Person implements IPerson {
  name: string
  age: number
  hobby?: string[]

  constructor(name: string, age: number, hobby: string[]) {
    this.name = name
    this.age = age
    this.hobby = hobby
  }
}

const output = new Person('john doe', 23, ['swimming', 'traveling', 'badminton'])
console.log(output)

Example 3: typescript class implements interface

interface Task{
    name: String; //property
    run(arg: any):void; //method
}

class MyTask implements Task{
    name: String;
    constructor(name: String) {
        this.name = name;
    }
	run(arg: any): void {
        console.log(`running: ${this.name}, arg: ${arg}`);
    }
}

let myTask: Task = new MyTask('someTask');
myTask.run("test");

Example 4: typescript interface

interface NumberOrStringDictionary {
  [index: string]: number | string;
  length: number; // ok, length is a number
  name: string; // ok, name is a string
}Try

Example 5: typescript type interface

//INTERFACE	                                TYPE
interface Animal {	                        type Animal = {
    name: string;	                            name: string;
}	                                        }
interface Bear extends Animal {	            type Bear = Animal & { 
    honey: boolean;	                            honey: Boolean;
}	                                        }

const bear = getBear();	                    const bear = getBear();
bear.name;	                                bear.name;
bear.honey;	                                bear.honey;