es6 typescript syntax for functions code example

Example 1: typescript arrow function

let sum = (x: number, y: number): number => {
    return x + y;
}

sum(10, 20); //returns 30

Example 2: 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());