toJSONintermediateconst d = new Date('2024-01-15T00:00:00.000Z')
d.toJSON() // β '2024-01-15T00:00:00.000Z'
JSON.stringify({ date: d }) // uses toJSON()Use toJSON() to get the ISO 8601 UTC string representation of a Date; it is called automatically by JSON.stringify.
toJSON() and toISOString() return the same string for a valid Date.
Challenge: Verify that new Date(0).toJSON() === new Date(0).toISOString().