How to Load a Script Only Once Using Local Storage in JavaScript

Discover a simple method to load a JavaScript script only once per user visit by effectively using `localStorage`.
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This video is based on the question stackoverflow.com/q/73456089/ asked by the user 'KSPR' ( stackoverflow.com/u/1055155/ ) and on the answer stackoverflow.com/a/73456127/ provided by the user 'Ivone Djaja' ( stackoverflow.com/u/8558174/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Load a Script Only Once: A Comprehensive Guide

When working on web applications, there might be scenarios where you want to execute a specific script only once for a user during their visit to a page. This is particularly useful on success pages, thank you pages, or any other scenario where repeated execution could be unnecessary or redundant. If you’ve ever found yourself tackling this problem, you are not alone! Let’s dive into how you can accomplish this using localStorage in JavaScript.

The Problem

Imagine you have a success page following a purchase and you want to track this event only one time per user visit. Your initial approach included checking if the user had already visited this page using localStorage. However, you faced an issue where your script kept running every time the page was loaded, regardless of the user's status. It’s crucial to implement a method that ensures your script executes only if the user is visiting for the first time.

The Solution: Using Local Storage

To effectively load a script only once, you can leverage the localStorage API to check if the user has visited the page before. Let’s break down the solution step by step.

Step 1: Check localStorage

Instead of checking if the item exists in localStorage and setting it afterwards, you want to ensure that your script runs when the condition evaluates to false. This way, if it's the user's first visit, the script should execute.

Step 2: Update the Condition

You need to modify your condition in such a way that it triggers on the first visit. Here’s the corrected code:

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

Explanation:

Check for Existence: The first line checks if "beenHere" is not present in localStorage. If this evaluates to true, it means the user is visiting the page for the first time.

Set Value: On the first visit, we set localStorage.setItem('beenHere', 1) to indicate that the user has now visited this page. This prevents the script from running again on future visits.

Script Execution: Inside the window.addEventListener, your goal-tracking code is executed, ensuring it only happens once when the user visits the success page.

Avoiding Common Mistakes

Ensure localStorage is Supported: Check for browser support for localStorage if you're targeting older browsers.

Clear Local Storage for Testing: If you're testing your code, remember to clear the localStorage or use a different browser or incognito mode to simulate a fresh visit.

Final Thoughts

Using localStorage for this purpose is relatively straightforward, provided you carefully manage your conditional checks. By ensuring your condition accurately reflects whether it's the user's first visit, you can confidently load scripts only when necessary. This not only improves your application’s efficiency but also enhances user experience by preventing unnecessary tracking or actions.

Now, with this approach, you can effectively control the execution of scripts on your pages, providing that clean and efficient solution you were looking for!



If you have any questions or need further clarification, feel free to leave a comment below. Happy coding!