Question

I’m building a web app that has a grid of many small scrollable divs (actually, Ace editors), and this grid has enough elements that it is larger than the window. When a user begins scrolling over empty space, I want them to be scrolling the window itself; when a user begins scrolling inside a grid element, I want them to scroll the div contents there. The thing is, if a user begins scrolling over empty space, and then scrolls such that their mouse goes over a grid element, that scrollable div captures all the scrolling events, interrupting the user’s flow over the grid and “trapping” them inside the grid element.

I can’t manually capture onmousewheel events, since AFAIK there’s no way to capture horizontal mouse wheel movement separately from vertical, and I want users on Mac OS X to be able to scroll in all directions. I’ve thought about using JS to add an invisible div with a very high z-index on the first onscroll event, and removing it as soon as onscroll events aren’t triggered for a certain period of time. Haven’t yet coded this up, but I’m wondering if there’s a better solution, or if there are any potential pitfalls that I haven’t thought of. Any help or advice would be great! Thanks!

Answer 1

I think a solution for this would be incredibly difficult due to browser support, and the actual solution, which would probably be something like calculating the scroll, backtracking the div, and applying the scroll to the page.

You could do something like this:

$('div').scroll(function(e){
    // figure out how much it has scrolled
    window.scrollBy(0,howmuch);
});

I don’t recommend this solution in the slightest though, I think the better option would be to set the divs to overflow:hidden; and pick up a solid scroll plugin, and use that to customize the scroll behavior on the divs.