Does Uncanny Dodge work automatically on every seen attack the rogue gets hit with?

@IHitItWithMyAxeHI Jeremy? Does uncanny dodge work automatically on every seen attack the rogue gets hit with? Magic too? Yep! Uncanny Dodge works against attacks of all sorts, even spell attacks.

— Jeremy Crawford (@JeremyECrawford) August 20, 2014

@nirvanstryder @IHitItWithMyAxedoes it work against each successful attack made by opponent who has multiple attacks or is it one attack A use of Uncanny Dodge works against one attack. Like Defensive Duelist, it expends your reaction.

— Jeremy Crawford (@JeremyECrawford) November 26, 2014