JSFiddle - React, Tailwind, and code Playground

HTML

<li onClick="return pop('pop')" id="stream">Link 5</li>
<div id="pop" class="parentDisable" onselectstart="return false" onselectstart="return false">
    <table border="1" id="popup">
        <tr>
            <td> <a href="" onclick="return hide('pop')" style="float: right; margin: 4px;">
                            <img src="http://www.imgbox.de/users/Metraax/close.png" />
                        </a>

            </td>
        </tr>
        <tr>
            <td>
                 <h2>Fenster ge&ouml;ffnet</h2>

            </td>
        </tr>
        <tr>
            <td>height: auto;</td>
        </tr>
    </table>
</div>

CSS

.parentDisable {
    z-index:999;
    width:100%;
    height:100%;
    display:none;
    position: absolute;
    top:0;
    left:0;
    background-color: rgba(204, 204, 204, 0.4);
    color: #aaa;
    filter: alpha(opacity=50);
}
#popup {
    width: 44.48%;
    position: absolute;
    top: 200px;
    left: 27.76%;
    color: #000;
    background-color: #C4C4C4;
    border-radius: 5px;
    box-shadow: 0px 0px 20px gray;
}
#popup tr td h2 {
    float: left;
    font-size: 20px;
}
#popup tr {
    cursor: default;
}

JavaScript

function pop(div) {
    var d = document.getElementById(div);
    d.style.display = 'block';
    
    if (document.addEventListener) {
        document.addEventListener ("keyup", function(e) {
            onEsc(e, d);
        }, false);
    }else{
        if (document.attachEvent)
            button.attachEvent ("keyup", function(e) {
                onEsc(e, d);
            });
    }
    return false
}

function hide(div) {
    document.getElementById(div).style.display = 'none';
    return false
}

function onEsc(event, elem) {
    if ( event.which == null && (event.charCode != null || event.keyCode != null) ) {
        event.which = event.charCode != null ? event.charCode : event.keyCode;
    }
    if (event.which === 27) {
        elem.style.display = 'none';
        document.removeEventListener("keyup");
    }
}