fix initial slideUp glitch in treeview

Author: danny007in

src/ts/treeview.ts

@@ -24,7 +24,7 @@ const EVENT_KEY = `.${DATA_KEY}`
 
 const EVENT_EXPANDED = `expanded${EVENT_KEY}`
 const EVENT_COLLAPSED = `collapsed${EVENT_KEY}`
-// const EVENT_LOAD_DATA_API = `load${EVENT_KEY}`
+const EVENT_LOAD_DATA_API = `load${EVENT_KEY}`
 
 const CLASS_NAME_MENU_OPEN = 'menu-open'
 const SELECTOR_NAV_ITEM = '.nav-item'
@@ -112,6 +112,18 @@ class Treeview {
  */
 
 onDOMContentLoaded(() => {
+  const openMenuItems = document.querySelectorAll(`${SELECTOR_NAV_ITEM}.${CLASS_NAME_MENU_OPEN}`)
+
+  openMenuItems.forEach(menuItem => {
+    const childElement = menuItem.querySelector(SELECTOR_TREEVIEW_MENU) as HTMLElement | undefined
+    if (childElement) {
+      slideDown(childElement, 0)
+
+      const event = new Event(EVENT_LOAD_DATA_API)
+      menuItem.dispatchEvent(event)
+    }
+  })
+
   const button = document.querySelectorAll(SELECTOR_DATA_TOGGLE)
 
   button.forEach(btn => {