Judging whether it is input to Chinese characters

I want to judge if the value of the string is Chinese or how is the letter?

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A bit wrong:

IF (/[1x00-/xff]/g.test(s)) ALERT ("With Chinese characters");

Else Alert ("all characters");

or:

If (/[/x00-/xff]/g.test (s)) ALERT ("contains characters");

Else Alert ("all is Chinese characters");