jQuery jQuery.parseJSON() Method

What You’ll Learn

The jQuery.parseJSON() utility converts a JSON string into a JavaScript value. This tutorial covers the official jQuery API example, parsing objects and arrays, error handling for malformed JSON, migration to JSON.parse(), and common pitfalls with quotes and control characters.

Introduction

Web apps constantly exchange data as JSON text — API responses, configuration files, and localStorage entries all arrive as strings that must become JavaScript objects before your code can use them.

jQuery added jQuery.parseJSON() (also written $.parseJSON()) in version 1.4.1 as a consistent parsing helper, especially for $.ajax callbacks that returned JSON as text. It was deprecated in jQuery 3.0 and removed in jQuery 4.0 in favor of the native JSON.parse() method built into every modern browser.

Understanding the jQuery.parseJSON() Method

jQuery.parseJSON(json) accepts one argument: a string containing valid JSON. It returns the parsed value — which may be an object, array, string, number, boolean, or null. It does not modify the original string.

JSON has strict rules: object keys must use double quotes, strings must use double quotes, and values like undefined or NaN are not allowed. Passing malformed JSON throws an exception — unlike some loose parsers, jQuery does not silently fix bad input.

📝 Syntax

General form of jQuery.parseJSON:

jQuery.parseJSON( json )
// or
$.parseJSON( json )

Parameters

• json — a string containing well-formed JSON to parse.

Return value

• The JavaScript value represented by the JSON string (object, array, string, number, boolean, or null).
• Throws a SyntaxError when the string is not valid JSON.

Official jQuery API example

var obj = jQuery.parseJSON('{ "name": "John" }');
console.log(obj.name === "John"); // true

Examples Gallery

Example 1 matches the official jQuery API documentation. Use DevTools or the Try-it links to run each snippet.

var obj = $.parseJSON('{ "name": "John" }');

console.log(obj.name);           // "John"
console.log(obj.name === "John"); // true

John
true

var json = '["HTML", "CSS", "JavaScript"]';
var langs = $.parseJSON(json);

console.log(langs.length);  // 3
console.log(langs[1]);      // "CSS"

3
CSS

var responseText = '{"status":"ok","user":{"id":42,"email":"dev@codetofun.com"}}';
var data = $.parseJSON(responseText);

console.log(data.status);       // "ok"
console.log(data.user.id);      // 42
console.log(data.user.email);   // "dev@codetofun.com"

ok
42
dev@codetofun.com

var badSamples = [
  '{test: 1}',           // keys need double quotes
  "{'test': 1}",        // single quotes invalid
  '"undefined"',         // undefined not allowed in JSON
  '".1"'                 // number needs leading digit
];

badSamples.forEach(function (sample) {
  try {
    $.parseJSON(sample);
    console.log("Unexpected success:", sample);
  } catch (err) {
    console.log("Rejected:", sample.slice(0, 12) + "...");
  }
});

Rejected: {test: 1}...
Rejected: {'test': 1}...
Rejected: "undefined"...
Rejected: ".1"...

var json = '{ "title": "CodeToFun", "year": 2026 }';

// Legacy jQuery (3.x still has it; removed in 4.0)
var withJquery = $.parseJSON(json);

// Modern native — use this in new code
var withNative = JSON.parse(json);

console.log(withJquery.title === withNative.title); // true
console.log(withNative.year);                       // 2026

true
2026

🚀 Common Use Cases

• AJAX text responses — parse responseText before jQuery auto-parsed JSON with dataType: "json".
• localStorage / sessionStorage — convert stored JSON strings back into objects.
• Configuration files — load JSON settings embedded in script tags or fetched at runtime.
• Plugin options — parse JSON from data-* attributes on DOM elements.
• Legacy code maintenance — read and refactor older jQuery projects using $.parseJSON.
• Validation pipelines — try/catch around parse to detect corrupt server output early.

📝 Notes

• Available since jQuery 1.4.1; deprecated in jQuery 3.0; removed in jQuery 4.0.
• Use JSON.parse() in all new code — identical behavior on valid JSON.
• Prior to jQuery 1.9, empty string / null / undefined input returned null instead of throwing.
• Literal tab/newline inside JSON strings can break parsing — escape backslashes in server output.
• Never use eval() to parse JSON — it executes arbitrary JavaScript.
• Pair with JSON.stringify() when writing values back to storage or APIs.

💡 Best Practices