Скачать или смотреть How to Store Multiple Values in HTML5 Local Storage: The Power of JSON Objects

Discover how to effectively use HTML5 Local Storage to store multiple values per key by leveraging JSON objects.
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Storing Multiple Values with HTML5 Local Storage: A Practical Guide

When working with HTML5 local storage, many developers encounter a common problem: they want to store multiple values under the same key, but they quickly realize that local storage is designed to hold only one value per key. This limitation can be frustrating, especially if your application requires saving the state of user inputs over time and enabling repeated submissions of a form. The good news? There’s a solution!

In this guide, we will explore how to use JSON objects to work around this limitation effectively.

Understanding Local Storage

Local storage is a powerful web storage feature that allows developers to store data in a web browser. Each key in local storage can only hold a single string value. If you save a new value under an existing key, it will overwrite the previous value. For example:

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As you can see in the example above, the last stored value is the only one that remains. If you want to store every entry made by a user, we need a different approach.

Solution: Using JSON Objects

Instead of trying to store multiple values as strings, we can utilize JavaScript objects and convert them to JSON strings when saving them to local storage. Here's how you can do that:

Initial Save: Creating the JSON Object

Start by creating an object to store the form values. Encapsulate the values into a JSON structure and store them using the setItem method.

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Updating Values: Adding New Entries

To add a new value to your JSON object stored in local storage, follow these steps:

Retrieve the existing formState object.

Add the new field.

Save the updated object back to local storage.

Here's how you can do this:

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Removing Entries: Deleting Specific Fields

If you want to remove a specific entry from the stored object, you can use the delete keyword. This allows you to remove any key-value pair from the object:

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Dumping Form Data into an Object

If you have a form and want to create an object based on all the inputs dynamically, the following code will help you achieve this:

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This script goes through all the inputs in your form, checks for conditions based on the type of input, and builds a comprehensive object ready for local storage.

Conclusion

Leveraging JSON objects allows you to effectively store multiple values under a single key in HTML5 local storage. This method not only adheres to the storage limitations but also makes your data handling much more flexible and robust. By masterfully combining JSON and local storage, you can truly enhance user interaction within your web applications.

With a clearer understanding of how to manage local storage, you're now equipped to handle multiple form submissions like a pro!