Primitives

Type	Notes
string	any string. Literal types narrow further ("red").
number	64-bit IEEE 754 float; includes NaN, ±Infinity.
bigint	arbitrary-precision integer.
boolean	true | false.
null / undefined	separate types; strictNullChecks keeps them out of other types unless explicitly added.
symbol	unique primitive identifier.
void	the absence of a return value; not the same as undefined.
never	the empty type; what a function returns if it always throws or never terminates.
any	opt-out of type checking. Avoid any; prefer unknown.
unknown	top type; must be narrowed before use.

References

• Casting for as, satisfies, and runtime validation.

• Types for the runtime types these annotate.