How to check if an element is visible after scrolling in AJAX

To check if an element is visible after scrolling in AJAX, we'll need to use JavaScript to handle the scroll event and determine the visibility status of the element.

AJAX is a technique for dynamically loading content without reloading the entire web page. The visibility of an element can change as the user scrolls down or up the page, and we need to be able to detect this change to perform any necessary actions.

Let's follow the step-by-step guide to achieve this:

1. First, we need to identify the element we want to check for visibility after scrolling. We can use the element's ID, class, or other suitable selector.

2. Attach a scroll event listener to the appropriate element to detect when the user scrolls. In most cases, we want to listen for the scroll event on the window or a specific container that contains the element.

3. Inside the scroll event handler, determine if the element is currently visible within the viewport. There are several ways to check for element visibility, but one common approach is to calculate the element's position relative to the viewport and compare it with the viewport's height.

Note: To view the output of the code. Open the "Inspect" window, go to the "Console" and tab on "user messages". Now move the scroll bar in the output pan. You will get messages every time when it's visible or not.

Code explanation

Let's explain the JavaScript code:

• Lines 2–10: This function checks whether an element is visible within the current viewport. It takes the element (el) as a parameter and uses the getBoundingClientRect() method to obtain the element's position relative to the viewport. The function then checks if all four sides of the element (top, left, bottom, and right) are within the viewport's boundaries, ensuring the element is fully visible. It returns true if the element is visible and false otherwise.

• Lines 12–21: The checkElementVisibility() function is responsible for checking the visibility status of a specific element with the ID yourElement. It calls the isElementVisible() function passing the target element as a parameter. If the element is visible, it logs "Element is visible" to the console; otherwise, it logs "Element is not visible".

Conclusion

Remember that AJAX doesn't directly affect the visibility of an element on the page; it's just a technique for loading content asynchronously. The visibility status of the element will be determined by its position relative to the viewport as the user scrolls.

It can be used in various scenarios where we need to trigger certain actions when an element comes into view or goes out of view during scrolling, for example, lazy loading of images or triggering animations when elements become visible.