Misplacing Semicolon

Due to a misplaced semicolon, this code block will execute regardless of the value of x.

if (x == 19);
{
// code block
}

Breaking a Return Statement

JavaScript automatically closes a statement at the end of a line by default.

As a result, these two examples will produce the same outcome:

function myFunction(a) {
let power = 10
return a * power
}

function myFunction(a) {
let power = 10;
return a * power;
}

JavaScript also allows you to split a statement across two lines.

Therefore, example 3 will produce the same result as well.

function myFunction(a) {
  let
  power = 10;
  return a * power;
}

But what happens if you split the return statement across two lines like this:

function myFunction(a) {
let
power = 10;
return
a * power;
}

The function will return undefined!

Why? Because JavaScript interprets it as:

function myFunction(a) {
let
power = 10;
return;
a * power;
}