Скачать или смотреть How to Properly Store an Array in a Cookie Using JavaScript

Learn how to store and retrieve arrays in cookies in JavaScript with simple methods. Follow our guide for clear explanations and examples!
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This video is based on the question https://stackoverflow.com/q/76052745/ asked by the user 'Mathieu' ( https://stackoverflow.com/u/1708580/ ) and on the answer https://stackoverflow.com/a/76052771/ provided by the user 'Bryce Chan' ( https://stackoverflow.com/u/6019358/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Properly Store an Array in a Cookie Using JavaScript

Storing arrays in cookies can be a useful technique when you need to maintain state or save user preferences on a web application. However, many developers face challenges when storing and retrieving arrays from cookies. If you've encountered an issue where your output is not as expected, you're not alone!

The Problem: Understanding the Issue

In a typical scenario, you might want to save arrays in cookies to use them later. However, if you try to log the output, you may find that your array isn't showing the structure you anticipated. Here’s an example of what can go wrong:

[[See Video to Reveal this Text or Code Snippet]]

When you see the above, the problem lies in how the variable arr is defined; it’s treated as a string rather than an actual array. This can lead to complications when you want to use it as an array after storing it in a cookie.

So how do we fix this?

The Solution: Steps to Store an Array in a Cookie

There are a few clear steps to follow in order to correctly store an array in a cookie using JavaScript.

1. Define the Array Correctly

Instead of defining arr as a string, you should declare it as an actual array. Here's how to do that:

[[See Video to Reveal this Text or Code Snippet]]

2. Stringify the Array

In order to store the array in a cookie, you need to convert it into a string format using JSON.stringify(). This method will convert the array into a JSON string.

[[See Video to Reveal this Text or Code Snippet]]

3. Set the Cookie

Now that we have the string representation of the array, we can set it as a cookie. We’ll assume you have a function called setCookie_text that takes the cookie name and value:

[[See Video to Reveal this Text or Code Snippet]]

4. Retrieve and Parse the Cookie

To retrieve the array later, you'll need to get that cookie back and parse it. Here’s how:

[[See Video to Reveal this Text or Code Snippet]]

Summary

By ensuring that you declare your array properly, stringify it before storing it in a cookie, and then parse it upon retrieval, you can maintain the structure of your data.

Key Points to Remember:

Always define your array using square brackets [].

Use JSON.stringify() to convert arrays to strings for storage.

Employ JSON.parse() to retrieve the original array format from the cookie.

Now you should be well on your way to successfully storing and retrieving arrays in cookies using JavaScript!