Do you know what will be the output of this code? function f(x = 10) { return x; } console.log(f(undefined), f(null));

When do default parameters apply in JavaScript?

Do you know what will be the output of this code?

JavaScript

function f(x = 10) {
  return x;
}

console.log(f(undefined), f(null));

Show answer and explanation

The answer is 10 null.

A default value is used only when the argument is missing or undefined. null is a real value, so it’s passed through.