JS Built-ins
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DatetoJSONbeginner

toJSON() — returns a string

📖 Usage Example
const d = new Date('2024-01-15T00:00:00.000Z')
d.toJSON()  // → '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.

Date.prototype.toJSON()

toJSON() always returns a string.

Challenge: Verify that typeof new Date(0).toJSON() returns 'string'.

💡 Hints (1)
  • • toJSON() returns a string primitive — the same ISO format used for JSON serialisation