字符串长度必须在 toUpperCase() 之后判断，否则可能会溢出~

[mytry]

'αß'.toUpperCase() === 'ΑSS'

...

'ffi'.toUpperCase() === 'FFI'

...

[yuikns]

'ffi' == '\ufb03'
true
'ß' == '\u00DF'
true

https://stackoverflow.com/questions/9127644


> "ß" character is equivalent to "ss" (used in German, for example), and this is defined so in your Locale (the Locale you are using in your app).

https://www.reddit.com/r/javascript/comments/9i455b

> When using capital letters, SS has historically stood for ß. However, in some fonts, there also exists a corresponding capital letter; its usage is optional <§ 25 E3>.

这个讨论还是挺多的。

不太明白 "否则可能会溢出" 这个结论。用啥字符串就拿啥 .length 呗。要是 for each，不妨试试 map foreach 等？

[mytry]

说错了不是溢出，应该是会被截断。