JSON.stringify() works well for plain JSON data, but it loses information for values like undefined, Date, and RegExp.

Popular libraries like SuperJSON and devalue were built to solve exactly this kind of problem.

Implement two functions:

• serialize(value): returns a string.
• deserialize(serialized): returns the original value represented by that string.

The exact serialized format is up to you. A common approach is to recursively convert the input into a JSON-safe tree with small tagged objects, then call JSON.stringify().

For this question, support:

• All normal JSON values
• undefined
• NaN, Infinity, -Infinity
• BigInt
• Date
• RegExp

Supported values can appear anywhere inside dense arrays and plain objects.

Examples

const value = {
  createdAt: new Date('2026-01-01T00:00:00.000Z'),
  retries: Infinity,
  missing: undefined,
  matcher: /user-\d+/gi,
};

const serialized = serialize(value);
// Any string format is fine as long as deserialize(serialized)
// recreates an equivalent value.

const restored = deserialize(serialized);

restored.createdAt instanceof Date; // true
restored.retries; // Infinity
restored.missing; // undefined
restored.matcher.test('USER-42'); // true

const value = [undefined, BigInt(42), { score: NaN }];
const restored = deserialize(serialize(value));

restored[0]; // undefined
restored[1]; // 42n
Number.isNaN(restored[2].score); // true

Notes

• You may assume deserialize only receives strings produced by serialize.
• Functions, symbols, symbol keys, Map, Set, cyclic references, sparse arrays, malformed serialized strings, and custom class instances are out of scope.

References

• SuperJSON
• devalue