struct.intersection

function intersection<
  const T extends readonly [
    StructLike<unknown, unknown, boolean>,
    ...StructLike<unknown, unknown, boolean>[],
  ],
>(
  ...structs: T
): T extends readonly [unknown]
  ? T[0]
  : T extends readonly [unknown, unknown, ...unknown[]]
    ? IntersectionStruct<T>
    : T[0] | IntersectionStruct<T>;

struct.intersection is variadic: pass each struct as its own argument.

• Parses the input with every struct and merges the results.

• When every struct is an object struct, the output is one object with the fields of all of them. Keys that none of them declares are removed.

• When two structs produce incompatible values for the same key, it fails with invalid_intersection.

• Accepts null only when every struct accepts it, including a nested intersection marked .null().

• A single struct is returned unchanged, so it keeps its own identity and type, including .optional() and .null(). Calling it with no structs throws TypeError, and so does a non-struct argument.

• A nonempty variadic tuple must account for that singleton. Spreading a tuple that may contain only one member infers both the singleton and multi-member results. Its object fields may therefore be optional. A tuple known to contain at least two members keeps the required intersection semantics.

IntersectionStruct<T> is not exported. It is a Struct whose input and output are the intersections of the member types.