Smi (small integer)

RU: Smi (small integer)

In the V8 JavaScript engine, a Smi (small integer) is an integer in the 31-bit signed range (32-bit on 64-bit builds without pointer compression) that V8 stores directly as a tagged pointer value rather than a heap-allocated object. Arithmetic on Smis avoids heap allocation and runs at native integer speed; writing a value outside the Smi range forces V8 to box it as a HeapNumber.