devalue/src/constants.js

Gets the job done when JSON.stringify can't

export const UNDEFINED = -1;
export const HOLE = -2;
export const NAN = -3;
export const POSITIVE_INFINITY = -4;
export const NEGATIVE_INFINITY = -5;
export const NEGATIVE_ZERO = -6;
export const SPARSE = -7;

// The largest valid value for a JavaScript array's `length` property,
// and the largest valid array index (one less than the max length).
export const MAX_ARRAY_LEN = 2 ** 32 - 1;
export const MAX_ARRAY_INDEX = MAX_ARRAY_LEN - 1;