what does return do in map javascript code example

Example 1: how to use the map method in javascript

const numbers = [1, 2, 3, 4, 5]; 

const bigNumbers = numbers.map(number => {
  return number * 10;
});

Example 2: functions in map javascript

const map = new Map();

function foo() {
 return "Hello World!"; 
}

map.set("foo", foo);

console.log(map.get("foo")()); // Output: "Hello World!