What does regex [\0-\uffff] capture?

As I开发者_如何学Python am reading through someone else's JavaScript, I encountered this regex charset:

[\0-\uffff]

What exactly is captured by this?

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That logical group will match every Unicode character between null and 0xffff

Nothing will actually be captured. For that you will have to use ( and )

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The set of characters whose code is within 0 to 0xffff.