Lesson 1.6Lesson 6 of 24
The JSON object
Given a JSON response, demonstrate how to operate the JSON object.
Key points
- 1JSON.parse turns JSON text into values and throws a SyntaxError for invalid text, so wrap untrusted input in try/catch.
- 2JSON.stringify takes a replacer, a function or an allow list of keys, and a number of spaces to indent.
- 3A reviver passed to JSON.parse sees every key and value, and can turn strings back into numbers or dates.
- 4Undefined values and functions are left out of objects and become null in arrays. NaN and Infinity become null.
- 5Dates become ISO strings and stay strings after parsing. Map and Set become empty objects.
What the exam guide checks here
Objective wording from the exam guide (English).
- 1.6.K1JSON.parse and JSON.stringify, including reviver, replacer and indentation
- 1.6.K2What JSON cannot represent: functions, undefined, Date objects, Map, Set
- 1.6.S1Read, change and serialize data from a JSON response
Lock it in
Answer scenario questions on this topic. Every option comes with an explanation.
Practise 1.6 · 12 questions