JS limit the number of bytes in the input box, two bytes in Chinese, one byte in English letters __JS

Maybe there are a lot of similar articles on the Internet, but here you should know, JS inside, Chinese and letter length is 1, but the database does not know Ah, a lot of database are in accordance with the byte, so, control the number of bytes in the input box seems to be more important than the length limit.

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1, the Limit text box is 16 bytes, only input Chinese and letters

Solution Idea:

1, the judgment can only be Chinese and English

2, the judge length can only be 16

3, there is a non conformance, will enter the loop:

The first step: Replace all the #, because I want to use this special character later

Step two: Replace all Chinese with: @@

Step three: Intercept the 0-20 byte length, where the Chinese has been turned into two lengths

Step Fourth: Convert all @@ 转换 #

Fifth step: Replace the last possible Chinese half byte, a @

Step sixth: Get the last remaining character length, which is the length of the string to intercept

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