JSON Parse

⬅️ JSON 🔗 Stack Overflow

• JSON.parse() parses a JSON string according to the JSON grammar, then evaluates the string as if it’s a JavaScript expression
• An optional reviver function can be provided to perform a transformation on the resulting object before it is returned.

const json = '{"result":true, "count":42}';
const obj = JSON.parse(json);
 
console.log(obj.count);
// Expected output: 42
 
console.log(obj.result);
// Expected output: true
 

More examples

JSON.parse("{}"); // {}
JSON.parse("true"); // true
JSON.parse('"foo"'); // "foo"
JSON.parse('[1, 5, "false"]'); // [1, 5, "false"]
JSON.parse("null"); // null
 

With reviver

JSON.parse(
  '{"p": 5}',
  (key, value) =>
    typeof value === "number"
      ? value * 2 // return value * 2 for numbers
      : value, // return everything else unchanged
);
// { p: 10 }
 
JSON.parse('{"1": 1, "2": 2, "3": {"4": 4, "5": {"6": 6}}}', (key, value) => {
  console.log(key);
  return value;
});
// 1
// 2
// 4
// 6
// 5
// 3
// ""