Showing posts with label after scroll. Show all posts
Showing posts with label after scroll. Show all posts

Thursday, December 22, 2016

jQuery Check if element is visible after scrolling

Html Part:

<script src="//ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<table style="width:100%;padding-top:100px;">
    <tr>
        <td style="width:50%;vertical-align:top">
            <h3>Partial Visibility Check</h3>

            <div class="scroll" style="height:320px;overflow:auto;border:1px solid blue;position:relative">
                <div class="check d1" style="height:100px;border:1px solid red">DIV 1</div>
                <div class="check d2" style="height:100px;border:1px solid red">DIV 2</div>
                <div class="check d3" style="height:100px;border:1px solid red">DIV 3</div>
                <div class="check d4" style="height:100px;border:10px solid red;padding-top:20px">DIV 4</div>
                <div style='padding:20px;position:relative;border:2px solid green;'>
                    <div style='border:2px solid blue;padding:30px;'>
                        <div class="check d5" style="height:100px;border:1px solid red">DIV 5</div>
                    </div>
                </div>
                <div class="check d6" style="height:100px;border:1px solid red">DIV 6</div>
                <div class="check d7" style="height:100px;border:1px solid red">DIV 7</div>
                <div class="check d8" style="height:100px;border:1px solid red">DIV 8</div>
            </div>
            <div class="log" style='height:140px;overflow:hidden'></div>
        </td>
        <td style="width:50%;vertical-align:top">
            <h3>Fully Visibility Check</h3>

            <div class="scroll full" style="height:320px;overflow:auto;border:1px solid blue;position:relative">
                <div style="height:3px"></div>
                <div class="check d1" style="height:100px;border:1px solid red">DIV 1</div>
                <div class="check d2" style="height:100px;border:1px solid red">DIV 2</div>
                <div class="check d3" style="height:100px;border:1px solid red">DIV 3</div>
                <div class="check d4" style="height:100px;border:1px solid red">DIV 4</div>
                <div class="check d5" style="height:100px;border:1px solid red">DIV 5</div>
                <div class="check d6" style="height:100px;border:1px solid red">DIV 6</div>
                <div class="check d7" style="height:100px;border:1px solid red">DIV 7</div>
                <div style="height:3px"></div>
            </div>
            <div class="log" style='height:128px;overflow:hidden'></div>
        </td>
    </tr>
</table>

jQuery Part:

var log = {};
$("div.scroll").scroll(function () {
    var boundary = $(this), block = boundary.closest("td"), full_view = boundary.hasClass("full");
    log = block.find(".log");
    boundary.find(".check").not(".visited").each(function () {
        var elem = $(this);
        var visited = isScrolledIntoView(boundary, elem, full_view);
        if (visited) {
            log.prepend("DIV.CLASS=\"" + elem.attr("class") + "\" VISITED<br/>");
        }
        else {
            log.prepend("DIV.CLASS=\"" + elem.attr("class") + "\" NOT VISITED<br/>");
        }
    });
});

function isScrolledIntoView(c, e, full_view) {
    var op = e[0].getBoundingClientRect().top - c[0].getBoundingClientRect().top;
    var oh = op + e[0].getBoundingClientRect().height;
    var v1 = c.height() > op && op >= 0;
    var v2 = oh <= c.height() && oh >= 0;
    return full_view === true ? (v1 && v2) : (v1 || v2);
}

Screenshot: