You can use only:
= Backspace
f = Form feed
= New line
= Carriage return
= tab
00 = octal character
x00 = hexadecimal character
u0000 = hexadecimal unicode character
So, you can insert different ASCII characters, but not format them (like italic or bold).
EDIT I also have to mention, that in fact alert
acts like toString
conversion, so including tags and/or styles is not possible.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…