Data Types & Type‑Coercion

Primitive types:

• Number – all numbers are floating point (NaN, Infinity).
• String
• Boolean
• null – intentional absence of any value.
• undefined – uninitialised.
• Symbol – unique identifiers.
• BigInt – arbitrarily large integers.

Objects, arrays and functions are reference types.

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Example: Type coercion pitfalls

'5' + 3   // "53" (string concatenation)
'5' - 3   // 2   (numeric subtraction)
true + 1  // 2   (true → 1)