设置上下文菜单的鼠标位置

document.addEventListener('contextmenu', function(event) {
    // 阻止默认的上下文菜单弹出
    event.preventDefault();
    // 获取鼠标位置
    var mouseX = event.clientX;
    var mouseY = event.clientY;
    // 设置菜单的位置
    setContextMenuPosition(mouseX, mouseY);
});

function setContextMenuPosition(x, y) {
    var contextMenu = document.getElementById('context-menu');
    contextMenu.style.left = x + 'px';
    contextMenu.style.top = y + 'px';
}

<div id="context-menu">
    <ul>
        <li>菜单项1</li>
        <li>菜单项2</li>
        <li>菜单项3</li>
    </ul>
</div>