JSFiddle - React, Tailwind, and code Playground

by BramVanroy

HTML

<div id="wrapper">
    <div id="inner">
        <button>Click me</button>
    </div>
</div>
<aside id="secondary"><ul></ul></aside>

<span data-begin="8" data-end="9" data-frame="verb(zijn,sg3,part_intransitive(toe))" data-id="18" data-infl="sg3" data-lcat="smain" data-lemma="toe_nemen" data-pos="verb" data-postag="WW(pv,tgw,met-t)" data-pt="ww" data-pvagr="met-t" data-pvtijd="tgw" data-rel="hd" data-root="neem_toe" data-sc="part_intransitive(toe)" data-sense="neem_toe" data-stype="declarative" data-tense="present" data-word="neemt" data-wvorm="pv" style="display:none"></span>

CSS

*, *:before, *:after {
    box-sizing:border-box;
}
body {
    height: 10000px;
}
#wrapper {
    width: 480px;
    height: 480px;
    line-height: 480px;
    overflow: auto;
    border: 3px solid #333;
}
#inner {
    width: 1280px;
    height: 100%;
    text-align: center;
}
aside {
    border: 6px solid #333;
    background: white;
    padding: 8px;
    position: fixed;
    top: 0;
    left: 0;
    font-size: 12px;
    font-family: sans-serif;
}
aside:after {
    content:"";
    position: absolute;
    left: 50%;
    top: -12px;
    margin-left: -3px;
    width: 0;
    height: 0;
    border-left: 6px solid transparent;
    border-right: 6px solid transparent;
    border-bottom: 6px solid #333;
}

aside > ul {list-style-position: inside;}

JavaScript

$("button").click(function () {
    var data = $("span").data(),
        sec = $("#secondary"),
        $this = $(this);
    
    sec.children("ul").empty();
    $("#wrapper").addClass("clicked");
    for (var i in data) {
        $("<li>", {
            html: "<strong>" + i + "</strong>: " + data[i]
        }).prependTo(sec.children("ul"));
    }
    
    // In this case the logs display the same values, in mine they don't.
    console.log("tooltip: " + sec.outerWidth() / 2);

    sec.css({
        "left": $this.offset().left + ($this.outerWidth() / 2) - (sec.outerWidth() / 2),
            "top": $this.offset().top + $this.outerHeight() + 12
    });

    console.log("tooltip: " + sec.outerWidth() / 2);
});