Mastering jQuery: How to Trigger a Function on Page Load and Scroll

Описание: Discover how to run a jQuery function on page load and scroll events, enhancing user interaction with your web application.
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This video is based on the question https://stackoverflow.com/q/66371163/ asked by the user 'Calvin Bonner' ( https://stackoverflow.com/u/2341519/ ) and on the answer https://stackoverflow.com/a/66371376/ provided by the user 'mplungjan' ( https://stackoverflow.com/u/295783/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Mastering jQuery: How to Trigger a Function on Page Load and Scroll

When developing interactive web applications, often you may need to manipulate elements based on user actions such as scrolling. If you're new to jQuery, you might wonder how to run a jQuery function attached to a specific element both on page load and when the element is scrolled. This post will guide you through that process step by step.

Understanding the Problem

You have a jQuery function that calculates the scroll position of a specific element and adjusts a progress bar accordingly. However, you want this same function to also execute when the page initially loads—especially if the content is already scrolled down to a certain position.

Your initial attempt involved trying to replace this.scrollTop in your jQuery code, but you encountered issues leading to NaN results. This can be frustrating for beginners, but fear not—there are ways to isolate the function so it can be invoked both during scrolls and on load.

The Solution

Let's break down how you can achieve this using two different approaches. We want to create a function that calculates the scroll position of an element and also triggers this function when the page loads.

1. Use a Named Function

The first approach is to define a named function and trigger it on page load.

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

2. Save a Reference to the Outer Element

Another method involves saving a reference to the outer element where the scrolling event occurs. This way, you easily reference the scroll position.

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

Conclusion

Whether you're binding a scroll event to a named function or maintaining a reference to the element, both approaches will let you efficiently trigger your jQuery function during page load and scrolling. Now, as you continue working with jQuery, you can enhance your web applications with greater interactivity.

If you have any questions or need further clarifications, feel free to ask. Happy coding!