JSON to JavaScript Object: Safe Parsing Guide

Basic JSON to object conversion

A valid JSON string becomes a JavaScript value: object, array, string, number, boolean, ornull.

const raw = '{"id":42,"name":"Alice","active":true}'
const user = JSON.parse(raw)

console.log(user.name)
// Alice

If you need the reverse direction, see JavaScript object to JSON.

Always catch parse failures

Invalid JSON throws a SyntaxError. This matters for user input, localStorage, uploaded files, query strings, and third-party API responses.

function parseJsonObject(raw) {
  try {
    return { ok: true, value: JSON.parse(raw) }
  } catch (error) {
    return {
      ok: false,
      error: error instanceof Error ? error.message : 'Invalid JSON'
    }
  }
}

If you are debugging a parser failure, the dedicated JSON.parse error guide covers the most common error cases.

Convert JSON to nested objects and arrays

JSON naturally supports nesting. The result is a normal JavaScript object tree that you can traverse with dot notation or array indexing.

const raw = '{"user":{"profile":{"name":"Alice"}},"roles":["admin","editor"]}'
const data = JSON.parse(raw)

console.log(data.user.profile.name)
console.log(data.roles[0])

For deeper structures and optional fields, read parse nested JSON in JavaScript.

Use a reviver for special value handling

A reviver runs after parsing and lets you convert specific values, such as ISO dates, into richer JavaScript objects.

const raw = '{"createdAt":"2024-01-15T10:30:00.000Z"}'

const result = JSON.parse(raw, (key, value) => {
  if (key === 'createdAt' && typeof value === 'string') {
    return new Date(value)
  }
  return value
})

Parsing is not validation

Parsed JSON can still be the wrong shape. Check required fields or validate with JSON Schema before trusting the data.

const payload = JSON.parse('{"email":123}')

if (typeof payload.email !== 'string') {
  throw new Error('email must be a string')
}

For reusable validation rules, see JSON Schema examples.