---
id: 6733ffacd0ad1e49ec2af051
title: How Can You Use Cookies to Store Arbitrary Data, Normally Controlled by HTTP Headers?
challengeType: 19
dashedName: how-can-you-use-cookies-to-store-arbitrary-data-normally-controlled-by-http-headers
---

# --description--

As you learned in previous lessons, cookies are simple data that websites can store on a user's device.

However, you can actually store more complex data structures in cookies. One common method is to use JSON to store objects or arrays. Here's an example:

```js
const userData = {
  name: "John Doe",
  age: 30,
  role: "admin"
};

document.cookie = "userInfo=" + JSON.stringify(userData) + "; path=/";
```

In this example, we're creating an object with user data, converting it to a JSON string, and then storing it in a cookie. When we want to retrieve this data, we can parse the JSON string into an object using `JSON.parse()`.

Now, you might be wondering about the "HTTP headers" aspect of our topic. Typically, cookies are set by the server using HTTP headers.

For example, a server might send a header like this:

```http
Set-Cookie: username=John Doe; expires=Thu, 31 Dec 2024 6:00:00 IST; path=/
```

This header tells the browser to set a cookie. 

We can also set cookies directly in the browser using JavaScript. This is useful for storing data that doesn't need to be sent to the server immediately.

Please note that cookies have a size limit of around 4KB, and storing too much data in them may slow down your web app.

Storing large amounts of data in cookies can increase network traffic as cookies are sent with every HTTP request.

# --questions--

## --text--

What is the purpose of the 'expires' parameter when setting a cookie?

## --answers--

It specifies which pages can access the cookie.

### --feedback--

Think about what happens to a cookie after a certain time has passed.

---

It sets the maximum size of the cookie.

### --feedback--

Think about what happens to a cookie after a certain time has passed.

---

It tells the browser when to delete the cookie.

---

It encrypts the cookie data.

### --feedback--

Think about what happens to a cookie after a certain time has passed.

## --video-solution--

3

## --text--

How can you store a complex data structure like an object in a cookie?

## --answers--

Objects can be directly stored in cookies.

### --feedback--

Consider what format might be used to represent an object as a string.

---

By converting the object to a JSON string.

---

By using multiple cookies for each object property.

### --feedback--

Consider what format might be used to represent an object as a string.

---

Complex data structures cannot be stored in cookies.

### --feedback--

Consider what format might be used to represent an object as a string.

## --video-solution--

2

## --text--

What is a potential drawback of storing large amounts of data in cookies?

## --answers--

It can slow down your web application.

---

Cookies have unlimited storage capacity.

### --feedback--

Think about what happens when cookies are sent with every HTTP request.

---

It makes the website more secure.

### --feedback--

Think about what happens when cookies are sent with every HTTP request.

---

It improves server performance.

### --feedback--

Think about what happens when cookies are sent with every HTTP request.

## --video-solution--

1
