I'm really new to Javascript and I heard about unicode characters, but I don't know how they work. I did this:

```
alert("U+00BF");

```

which is the unicode for an upside-down question mark, but for some reason it just alerts the letters "U+00BF". I've tried using unicode characters with a format more like this:

```
alert("/xF3");

```

and those worked, but I don't know what I'm doing wrong with the first one. Does anyone know?