Скачать или смотреть Resolving List Duplication in JavaScript: Update Instead of Add character ranking

Learn how to update a ranking list in JavaScript without duplicating items. This guide breaks down the solution step by step, making it easy to fix your code.
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This video is based on the question https://stackoverflow.com/q/62984866/ asked by the user 'Marten Prod' ( https://stackoverflow.com/u/13908117/ ) and on the answer https://stackoverflow.com/a/62985143/ provided by the user 'Jan Stránský' ( https://stackoverflow.com/u/2700104/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving List Duplication in JavaScript: Update Instead of Add character ranking

When working with arrays in JavaScript, especially for tasks that involve user interactions like button clicks, you might encounter a common problem: duplicating list entries instead of updating them. This issue can be particularly frustrating when dealing with ranking systems or scoreboards. Let's dive into a specific scenario and its solution.

The Problem

In our scenario, we have a list of characters, each with an associated score. Whenever a user clicks the respective button for a character, their score should increase by one. Additionally, when the user clicks the "Rank Characters" button, the current rankings should be displayed without duplicating lists or entries. However, many are finding that each click adds another list instead of updating the existing one, leading to confusion and clutter in the HTML output.

The Current Code Structure

Here's a quick review of how the code currently works:

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

The issue arises from the rank function, which appends new list items to the existing list without removing the previous entries.

The Solution: Clearing the List before Updating

To resolve the problem of duplicating entries, we need to clear the existing list before appending new rankings. This can be done by setting the inner HTML of the rankings element to an empty string before building the new list.

Updated Function Code

Here's the corrected rank function:

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

Explanation

Clearing the List: el.innerHTML = ""; ensures that the list is empty before we add new ranked characters. This prevents any previous entries from lingering in the HTML output.

Updating the List: After clearing, we iterate through the characters array and create new list items for the current ranking, which will now only reflect the current scores correctly.

Conclusion

By implementing a simple line of code to clear the existing list, we tackle the problem of duplicate entries head-on. This not only simplifies the code but also enhances the overall user experience by providing a clear and accurate ranking system.

If you come across any similar issues with your JavaScript projects, remember that a quick review of how data is rendered can often lead to effective solutions. Happy coding!