typescript interface

1interface IEmployee {
2    empCode: number;
3    empName: string;
4    getSalary: (number) => number; // arrow function
5    getManagerName(number): string; 
6}
7

1interface IPerson {
2  name: string
3  age: number
4  hobby?: string[]
5}
6
7class Person implements IPerson {
8  name: string
9  age: number
10  hobby?: string[]
11
12  constructor(name: string, age: number, hobby: string[]) {
13    this.name = name
14    this.age = age
15    this.hobby = hobby
16  }
17}
18
19const output = new Person('john doe', 23, ['swimming', 'traveling', 'badminton'])
20console.log(output)
21

1type ValueOf<T> = T[keyof T];

1// https://stackoverflow.com/a/41967120
2// `I` Prefix not recommended : 
3// Ref : https://stackoverflow.com/a/41967120, 
4//       https://github.com/Microsoft/TypeScript/wiki/Coding-guidelines
5interface SquareConfig {
6  color?: string;
7  width?: number;
8  [propName: string]: any;
9}
10
11interface StringArray {
12  [index: number]: string;
13}
14 
15let myArray: StringArray;
16myArray = ["Bob", "Fred"];
17 
18let myStr: string = myArray[0];
19

1interface Foo {
2    bar: string;
3    qux: number;
4}
5// Creates object implementing interface:
6const MyFoo = <Foo> {
7    bar: "Hello",
8    qux: 7
9}
10// Or:
11const MyFoo: Foo = {
12    bar: "Hello",
13    qux: 7
14}

1interface LabeledValue {
2  label: string;
3}
4
5function printLabel(labeledObj: LabeledValue) {
6  console.log(labeledObj.label);
7}
8
9let myObj = { size: 10, label: "Size 10 Object" };
10printLabel(myObj);Try
11