The JavaScript JSON.parse() method

Q: What is the difference between JSON.parse() and JSON.stringify()?

JSON.parse() turns a string into a value; JSON.stringify() turns a value into a string. They're inverses.

Q: Do I need JSON.parse() with fetch()?

Usually not — await response.json() parses the response body for you. Use JSON.parse() when you already have a JSON string.

Method JavaScript All modern browsers Updated June 23, 2026

Quick answer

The JSON.parse() method turns a JSON string into a JavaScript value. JSON.parse('{"a":1}') gives the object {a: 1}. You use it to read data that arrived as text — from an API or localStorage. Wrap it in try/catch, because invalid JSON throws a SyntaxError. Its inverse is JSON.stringify().

Overview

JSON.parse() is how data comes into your program: it takes a JSON-formatted string and rebuilds it as a real JavaScript object or array you can work with. Anything stored as text — an API response read as a string, a value pulled from localStorage — needs parsing before you can access its properties.

It's the mirror image of JSON.stringify(): stringify goes object-to-string, parse goes string-to-object. Together they round-trip data through any text channel. Note that most fetch() code uses response.json() instead, which parses for you — you reach for JSON.parse() directly when you already hold a string.

The one rule you must not skip: wrap it in try/catch. If the string isn't valid JSON — a truncated response, an empty localStorage value, a stray trailing comma — JSON.parse() throws a SyntaxError and crashes that code path. Catching it lets you fall back gracefully. An optional second argument, a reviver function, can transform values as they're parsed (for example, turning date strings back into Date objects).

Syntax

const value = JSON.parse(text)
const value = JSON.parse(text, reviver)

JSON.parse('{"a":1}')   // { a: 1 }
JSON.parse('[1, 2, 3]') // [1, 2, 3]

Parameters

The JSON.parse() method accepts the following parameters.

Parameter	Description
`text`	The JSON string to parse. Must be valid JSON or it throws a `SyntaxError`.
`reviver`	Optional. A function called for each key/value to transform values as they are parsed.

Example

Live example

<pre id="out" style="font:15px ui-monospace,monospace"></pre>
<script>
  const text = '{"name":"Ada","age":36}';

  try {
    const user = JSON.parse(text);
    document.getElementById('out').textContent =
      user.name + ' is ' + user.age; // Ada is 36
  } catch (err) {
    document.getElementById('out').textContent = 'Invalid JSON';
  }
</script>

Best practices

Always wrap JSON.parse() in try/catch — invalid JSON throws a SyntaxError.
Pair it with JSON.stringify() to round-trip data through text storage.
When using fetch(), prefer await response.json(), which parses the body for you.
Use a reviver to restore special types, like turning ISO date strings back into Date objects.

Frequently asked questions

What does JSON.parse() do?

It converts a JSON string into a JavaScript object, array, or other value you can use in code.

Why does JSON.parse() throw an error?

Because the string isn't valid JSON — perhaps empty, truncated, or with a trailing comma. Wrap the call in try/catch to handle it.

What is the difference between JSON.parse() and JSON.stringify()?

JSON.parse() turns a string into a value; JSON.stringify() turns a value into a string. They're inverses.

Do I need JSON.parse() with fetch()?

Usually not — await response.json() parses the response body for you. Use JSON.parse() when you already have a JSON string.

date.toLocaleDateString() JSON.stringify()

References