Edit in JSFiddle

        $(document).ready(function () {
            $(".parent").jQContextMenu({
                selector: ".showMenu",
                target: "#menu",
                // Always position to the left of the context element.
                position: function (options, x, y) {
                    var element = options.currentElement[0];
                    var menu = options.menuParent;
                    var diffHeight = element.offsetHeight - menu.height();
                    menu.css({ top: element.offsetTop + diffHeight, left: element.offsetLeft });
                },
                itemClick: function (event, ui) {
                    var text = $(ui.items[0]).text();
                    alert("You clicked on " + text);
                }
            });
         });

<div class="parent" style="z-index:20; color:white;  margin-left:20%; margin-right:20% ">
        <span style="color:#4E4D4D; font-size:24px; font-family:Segoe UI;">Custom Menu Position</span>
        <div class="showMenu" style="margin-top:30px; padding: 60px 60px 60px 120px; background-color:rgb(163, 163, 163); font-size:25px;">Right Click here to Show Context Menu</div>
        <div  style="color:#4E4D4D; margin-top:50px; font-size:18px; font-family:Segoe UI;">This sample illustrates how to change the Context Menu current position</div>
    </div>
    <ul id="menu">
       <li><span class="ui-icon ui-icon-scissors"></span>Cut</li>
         <li><span class="ui-icon ui-icon-copy"></span>Copy</li>
        <li><span class="ui-icon ui-icon-copy"></span>Paste</li>
        <li>-----</li>
        <li>Edit</li>
        <li>Other Options<ul><li>Option1</li><li>Option2</li></ul></li>
    </ul>
<br/>
<p><font size="3"><b>Source for this<a  target="_blank"href="http://jqfaq.com/jquery-ui-context-menu-plugin/"</a> JQFaq Question</b></font></p>
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