Do you know what will be the output of this code? function add(a, b) { return a + b; } console.log(add(1));

What happens when you call a function with missing arguments?

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

JavaScript

function add(a, b) {
  return a + b;
}

console.log(add(1));

Show answer and explanation

The answer is NaN.

JavaScript doesn’t check the number of arguments. b is undefined, and 1 + undefined is NaN. A default like b = 0 avoids this.