How to Prevent Parent Element Scrolling When a Fixed and Scrollable Child Element Reaches Its Edge?

Prevent Parent Element Scrolling When Child Reaches Edge

When utilizing a fixed and scrollable element within its parent, it may be desirable to restrict the parent's scrolling when the child element reaches its top or bottom. This issue arises when scrolling within the child element and the parent element takes over, causing unwanted scrolling in the background.

Attempted Solution and Its Limitation

Initially, the event.stoppropagation() method was employed to halt event propagation. However, this method proved ineffective as propagation still occurred.

Comprehensive Solution

A more effective solution involves handling the mousewheel event using jQuery. The solution utilizes the wheelDelta property, where positive values indicate scrolling up and negative values indicate scrolling down.

Here is a detailed explanation of the script:

1. Event Handling: The jQuery code listens for both 'DOMMouseScroll' (for Firefox) and 'mousewheel' events (for other browsers) on elements with the '.Scrollable' class.
2. Scrolling Direction Detection: The delta value is used to determine the scrolling direction.
3. Prevent Default Action: A prevent function is defined to halt scrolling.
4. Edge Case Checks: The script checks for edge cases where scrolling would surpass the minimum or maximum position of the scrollable element.
5. Adjusting Scroll Position: If an edge case is detected, the script sets the scrollTop value to either 0 (top) or the scrollHeight (bottom) of the scrollable element.
6. Event Cancellation: The prevent function is executed to cancel the event entirely, ensuring that it does not propagate to the parent element.

By utilizing this solution, unwanted scrolling in the parent element can be effectively prevented, regardless of the browser being used.

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