typescript set return type code example

Example 1: typescript function as parameter

function createPerson(name: string, doAction: () => void): void {
  console.log(`Hi, my name is ${name}.`);
  doAction(); // doAction as a function parameter.
}

// Hi, my name is Bob.
// performs doAction which is waveHands function.
createPerson('Bob', waveHands());

Example 2: typescript function type

// define your parameter's type inside the parenthesis
// define your return type after the parenthesis

function sayHello(name: string): string  {
  console.log(`Hello, ${name}`!);
}

sayHello('Bob'); // Hello, Bob!

Example 3: function with return type in angular

greet() : number {
    return "Hello, " + this.greeting;
}

Example 4: typescript annotate return type

function add(x: number, y: number): number {
  return x + y;
}