
Expressions like `index = index + 1` occur quite often in JavaScript, so the creators of the language added a shortcut: `index += 1`. This shortcut is usually referred to as syntactic sugar because it simplifies and "sweetens" the process of coding :)

There are shortcuts for all arithmetic operations and for string concatenation:

- `a = a + 1` → `a += 1`
- `a = a - 1` → `a -= 1`
- `a = a * 2` → `a *= 2`
- `a = a / 1` → `a /= 1`
- `a = a + 'foo'` → `a += 'foo'`
