set return type of function typescript code example

Example 1: typescript default parameter

// Default Parameters
sayHello(hello: string = 'hello') { 
    console.log(hello); 
}

sayHello(); // Prints 'hello'

sayHello('world'); // Prints 'world'

Example 2: simple function in typescript

// Named function

//function with type as number
function add(x: number, y: number): number {
  // return sum of numbers entered as params
  return x + y;
}

// Anonymous function

// variable to call and define function
let myAdd = function (x: number, y: number): number {
  // return sum of numbers entered as params
  return x + y;
};

Example 3: get function return type typescript

type return_type = ReturnType<() => string>; // string
// or
function hello_world(): string {
  return "hello world";
}
type return_type = ReturnType<typeof hello_world>; // string