Also, every week I send my "3-2-1" frontend newsletter with 3 hand-picked articles from me, 2 web development guides from others, and 1 useful Tweet I enjoyed.
Here the simple cheat sheet that can save you hours per week
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100 - Continue
Server is satisfied with the initial information about the request and client can continue to forward headers.
101 - Switching Protocols
The server suggests switching to a protocol more suitable for the specified resource. (list of proposed protocols server indicates in the header field `Upgrade`)