Scroll to top of a specific class within a scrollable div - on each click of up/down button

Question

I have an RSS blog feed (hidden overflow) with buttons on the top and bottom of the div which will smoothly scroll through-out the feed. I'm looking for a way so that on each button click, it will scroll to the top of the next 'rss-item' (class). The div looks like this:

So what I'm trying to achieve is so each time you click the down arrow (or up) the scroll will stop when each 'rss-item' is at the top of the div. I explored many similar questions but couldn't quite achieve what I wanted.

Here is the function used to smooth scroll within the div:

 $(document).ready(function() {

    var scrollTime = 900;

$('#upClick').click(function() {
    $('#homeBlogs').animate({
        scrollTop: $('#homeBlogs').scrollTop() + 200
    }, scrollTime);
});


$('#downClick').click(function() {
    $('#homeBlogs').animate({
        scrollTop: $('#homeBlogs').scrollTop() - 200
    }, scrollTime);
});


});

Here is a screen grab of the generated source html:

Answer 1

Ok, so I re-created this as best I could in a jsfiddle. Here is the HTML structure. I've tried to build this according to the screenshot so they should be similar. Note: I've added a CSS class of "active" to the first "rss-item". This should only be applied in HTML to the first item and needs to stay here in order for the Javascript portion to function correctly.

<div id="blogSection">
    <div class="row" id="scrollUp">
        <button class="scrollButton" id="upClick">Scroll Up</button>
    </div>
    <div id="homeBlogs">
        <div class="rss-box">
            <p class="rss-title"></p>
            <ul class="rss-items">
                <li class="rss-item active">
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                </li>
                <li class="rss-item">
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                </li>
                <li class="rss-item">
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                </li>
                <li class="rss-item">
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                </li>
                <li class="rss-item">
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                </li>
                <li class="rss-item">
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                    <p>ContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContentContent</p>
                </li>
            </ul>
        </div>
    </div>
    <div id="scrollDown" class="row">
        <button class="scrollButton" id="downClick">Scroll Down</button>
    </div>
</div>

Next, here is the CSS I used. This is purely to support the demo. I set it up so whichever "rss-item" has the "active" class will be highlighted in red. This should hopefully provide a visual cue as to what's going on when a button is clicked.

button {
    display: block;
    width: 100%;
    background-color: black;
    color: white;
    height: 50px;
    cursor: pointer;
}

#scrollUp {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
}

#scrollDown {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
}

.active {
    color: red;
}

Finally, here is the Javascript I used in order to get things done. I've changed it a lot to help make things more efficient and to correct some errors.

$(document).ready(function() {})
//we can use one single event and modify the behavior based on the direction that was clicked
.on('click', '.scrollButton', function() {
    var scrollTime = 900,
        direction = $(this).attr('id'),
        $currentItem = $('.rss-item.active'),
        $newItem;

    switch (direction) {
        case 'upClick':
            $newItem = $currentItem.prev('.rss-item');
        break;

        case 'downClick':
            $newItem = $currentItem.next('.rss-item');
        break;
    }

    //if we aren't at the top or bottom of the list already
    if ($newItem.length > 0) {
        //since we know we can now change the active item, we need to remove this class so we can apply it to the new item
        $('.rss-item').removeClass('active');

        $newItem.addClass('active');
    }

    //Now that the logic is out of the way, we can run the scroll animation
    //Also, I think you will want to use 'html, body' as a selector so the page itself moves
    $('html, body').animate({
        scrollTop: $('.rss-item.active').offset().top - 200 //this will keep content positioned correctly, but you shouldn't need both a '+ 200' and '- 200' here. Adjust this value as needed.
    }, scrollTime);
});

Finally, here is the jsfiddle: https://jsfiddle.net/sm1215/sebgbnr4/