All 10 JSON & Data Serialization questions
More in JSON & Data Serialization
How do you convert a JavaScript object into a JSON string? What values does JSON.stringify() silently drop or convert, and why does this matter? How do you use the replacer parameter of JSON.stringify() to control what gets serialized? How does the reviver function in JSON.parse() work? Why does JSON.stringify() throw a TypeError on objects with circular references, and how do you handle it? How does defining a toJSON() method on a class customize its JSON.stringify() output? What is structuredClone() and how does it differ from JSON.parse(JSON.stringify(obj)) for deep cloning? How do you safely parse potentially untrusted JSON without exposing your app to prototype pollution? How would you stream-parse a very large JSON file without loading it entirely into memory?
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How do you convert a JSON string back into a JavaScript object?

Beginner

Answer

JSON.parse() parses a JSON-formatted string and returns the corresponding JavaScript value (object, array, string, number, etc.); it throws a SyntaxError if the string isn't valid JSON.
const json = '{"name":"Sam","age":30}';
const obj = JSON.parse(json);
console.log(obj.name); // 'Sam'
Real-world example Parsing a JSON response body received from an API into a usable JavaScript object.

Common follow-ups: How do you safely handle a JSON.parse() call that might fail on malformed input?

Error Handling
All 10 JSON & Data Serialization questions