How to Fix TypeError: Converting circular structure to JSON in JavaScript

The TypeError: Converting circular structure to JSON occurs when you try to convert an object that has a reference to itself into a JSON string.

The example code that causes the error looks like this:

let user = { name: 'Nathan' };

user.comment = user;


Here, you can see that the user object has a property called comment that got assigned the user object itself. This is what JavaScript meant with a circular reference.

When you pass an object with a circular reference to the JSON.stringify() method, you get this error:

Uncaught TypeError: Converting circular structure to JSON
    --> starting at object with constructor 'Object'
    --- property 'comment' closes the circle
    at JSON.stringify (<anonymous>)
    at <anonymous>:5:6

The solution to fix this error is simple: You need to avoid referencing the object itself into one of its properties as shown above, and the JSON.stringify() method should work.

let user = { name: 'Nathan' };

user.comment = ''; // pass an empty string

JSON.stringify(user); // ✅

If you really need to refer to the object itself in your code, then you can install the flatted package that can convert a circular structure without any issue.

Install the package, then import it into your code as follows:

const {parse, stringify} = require('flatted');

let user = { name: 'Nathan' };

user.comment = user;

// convert to JSON
let myJson = stringify(user);

// convert back to object
let myObject = parse(myJson);

You can use the stringify() method from flatted to convert an object into a JSON string, then use the parse() method to convert the JSON string back to an object.

And that’s how you solved the TypeError: Converting circular structure to JSON in JavaScript.

I also have more articles related to JSON manipulations in JavaScript as follows:

These articles should help you in working with JSON data in JavaScript. Happy coding!

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