refactoring of tree context menu into reusable component

src/public/javascripts/services/context_menu.js

@@ -0,0 +1,65 @@
+const $contextMenuContainer = $("#context-menu-container");
+
+function initContextMenu(event, contextMenuItems, selectContextMenuItem) {
+    $contextMenuContainer.empty();
+
+    for (const item of contextMenuItems) {
+        if (item.title === '----') {
+            $contextMenuContainer.append($("<div>").addClass("dropdown-divider"));
+        } else {
+            const $icon = $("<span>");
+
+            if (item.uiIcon) {
+                $icon.addClass("jam jam-" + item.uiIcon);
+            } else {
+                $icon.append("&nbsp;");
+            }
+
+            const $item = $("<a>")
+                .append($icon)
+                .append(" &nbsp; ") // some space between icon and text
+                .addClass("dropdown-item")
+                .prop("data-cmd", item.cmd)
+                .append(item.title);
+
+
+            if (item.enabled !== undefined && !item.enabled) {
+                $item.addClass("disabled");
+            }
+
+            $item.click(async function (e) {
+                const cmd = $(e.target).prop("data-cmd");
+
+                await selectContextMenuItem(e, cmd);
+            });
+
+            $contextMenuContainer.append($item);
+        }
+    }
+
+    // code below tries to detect when dropdown would overflow from page
+    // in such case we'll position it above click coordinates so it will fit into client
+    const clickPosition = event.pageY;
+    const clientHeight = document.documentElement.clientHeight;
+    const contextMenuHeight = $contextMenuContainer.height();
+
+    let top;
+
+    if (clickPosition + contextMenuHeight > clientHeight) {
+        top = clientHeight - contextMenuHeight - 10;
+    } else {
+        top = event.pageY - 10;
+    }
+
+    $contextMenuContainer.css({
+        display: "block",
+        top: top,
+        left: event.pageX - 20
+    }).addClass("show");
+}
+
+$(document).click(() => $contextMenuContainer.hide());
+
+export default {
+    initContextMenu
+}