ARTICLE AD BOX
This is because you used a wrong syntax for the arrow function passed to numbers.map.
This is the fix:
const numbers = [1, 2, 3, 4];
const doubled = numbers.map(num => num * 2);
console.log(doubled);
Alternative Fix:
Alternatively, you could have used the block syntax for your arrow function, but then it should be fixed just by adding the keyword return:
const numbers = [1, 2, 3, 4];
const doubled = numbers.map(num => {
return num * 2;
});
console.log(doubled);
In this particular case, the block {...} can be considered redundant. The shorter first variant would suffice.
Background:
When you use the arrow function syntax with {...}, you have to use return statement inside the curly brackets, but it was missing. And a function with missing return actually returns undefined.
![Artificial Intelligence decision making [closed]](https://stackoverflow.com/Content/Sites/stackoverflow/Img/apple-touch-icon@2.png?v=0f0cab681579)