Generate unique random string with Javascript

Question

I am creating an app where I sometimes need to allow user to generate some random strings. I would like to force that to be generated in the following format:

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xxxx-xxxx-xxxx

Where "x" is some number [0-9] or character [A-Z]. What would the most efficient way to do this? When generated, I would also need to check does it already exist in database so I am a little bit worried about the time which it would take.

Answer 1

We can make it so simple like

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require("crypto").randomBytes(64).toString('hex')