Discussion on: how not to use reduce

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Replies for: Try it out. Try to write code in a way so that "it explains itself" and doesn't require comments. Optimise only the complexity (big-O) of the code;...

I believe you are right, though the implementation of Set in javascript should give O(1) or at most sublinear lookups with a hashing function. Based on that, I assume the following would be equivalent without the new data type.

const jObj = ys.reduce((t, c) => { t[c] = true; return t; });
xs.find(x => ( jObj[x] ));

YCM Jason • Jul 1 '20

ya except I'd not use a reduce.