ECMA-262（JavaScript 5版）中的“代码单元值”是什么意思？

Question

I'm watching ECMA-262 (JavaScript 5 edition) and cannot understand what is "code unit value"?

Can anyone tell me?

Thank you very much!

Answer 1

A JavaScript string is a sequence of unsigned 16-bit integers, also known as code units .

A code point is how the Unicode standard represents symbols and non-symbols. Code points are represented as a four-to-six digit hexadecimal number, typically prefixed with U+ , eg U+0061 LATIN SMALL LETTER A.

The difference is that what can be part of a code unit depends on the character encoding that is used. A code point however, is merely the concept of a “character” that can then potentially be encoded using UTF-8, for example.

For more information, read chapter 2 of the Unicode spec , especially 2.4 Code points and characters .