Platforms & theory

Data Types

Numbers, collections, nulls, strings — what the bits actually mean.

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175 XP
Primitives & Numbers
Int, float, decimal — and why 0.1 + 0.2 isn't 0.3.
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200 XP
Collections
Array, list, map, set, tuple — when to reach for each.
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225 XP
Value vs Reference
Aliasing, shallow copy, mutation through a handle.
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200 XP
Nullability
null, undefined, NaN — three ways to say 'no value'.
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250 XP
Strings & Encodings
UTF-8, UTF-16, surrogates, graphemes — why string length is a trick question.
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