Make Dropdown to Process List Scroll Properly

src/app/components/dropdown/dropdown.html

@@ -1,24 +1,30 @@
+<ng-template #inputTemplate>
+  <div #searchInput class="dropdown-input" [class.hidden]="!isOpen()" [class.focus-mode]="inputFocusMode()"
+    contenteditable="true" role="textbox" aria-multiline="false" [aria-placeholder]="translation.common.selectOption" [aria-activedescendant]="ariaActiveDescendant()"
+    [attr.placeholder]="translation.common.selectOption" tabindex="-1" spellcheck="false"
+    (input)="onSearch($event)" (click)="handleInputClick($event)" (mousedown)="handleInputMouseDown()" (beforeinput)="preprocessInputContent($event)"></div>
+</ng-template>
+
 <div class="dropdown-box">
   @if (icon()) {
     <span class="material-symbols-outlined icon-24 prefix-icon">{{ icon() }}</span>
   }
 
-  @if (isOpen()) {
-    <div #searchInput class="dropdown-input" [class.hidden]="!isOpen()" [class.focus-mode]="inputFocusMode()"
-       contenteditable="true" role="textbox" aria-multiline="false" [aria-placeholder]="translation.common.selectOption"
-       [attr.placeholder]="translation.common.selectOption" tabindex="-1" spellcheck="false"
-       (input)="onSearch($event)" (click)="handleInputClick($event)" (mousedown)="handleInputMouseDown()" (beforeinput)="preprocessInputContent($event)">{{ this.initialInputText() }}</div>
-  } @else {
+  @if (recreateKey() % 2 == 0) {<ng-container [ngTemplateOutlet]="inputTemplate" />}
+  @else {<ng-container [ngTemplateOutlet]="inputTemplate" />}
+
+  @if (!isOpen()) {
     <span class="placeholder">{{ selectedLabel() }}</span>
   }
   <span class="material-symbols-outlined icon-24 chevron" [class.open]="isOpen()">keyboard_arrow_down</span>
 </div>
 
 @if (isOpen()) {
-  <div class="dropdown-container">
-    <ul class="dropdown-list" role="listbox" [id]="dropdownId + '-listbox'">
+  <div class="dropdown-container" tabindex="-1">
+    <ul class="dropdown-list" role="listbox" [id]="dropdownId + '-listbox'" tabindex="-1">
       @for (option of filteredOptions(); track option.value; let i = $index) {
         <li
+          #optionItem
           class="dropdown-item"
           role="option"
           [id]="dropdownId + '-option-' + i"

src/app/components/dropdown/dropdown.scss

@@ -186,7 +186,7 @@ $default_animation_duration: 0.2s;
   padding: 0 16px;
   position: relative;
   align-content: center;
-  transition: --hover-state var(--animation-duration) $animation_timing, --selected-state var(--animation-duration) $animation_timing;
+  transition: --hover-state calc(var(--animation-duration) / 3) $animation_timing, --selected-state calc(var(--animation-duration) / 3) $animation_timing;
   font-size: 16px;
 
   background-color: color-mix(
@@ -201,6 +201,10 @@ $default_animation_duration: 0.2s;
     calc(var(--selected-state) * 100%)
   );
 
+  &.focused {
+    --animation-duration: 0;
+  }
+
   &:hover, &.focused {
     --hover-state: 1;
   }

src/app/components/dropdown/dropdown.ts

@@ -11,9 +11,11 @@ import {
   inject,
   effect,
   viewChild,
+  viewChildren,
   untracked,
+  PLATFORM_ID,
 } from '@angular/core';
-import { CommonModule } from '@angular/common';
+import { CommonModule, isPlatformBrowser } from '@angular/common';
 import { TranslationService } from '../../services/translation.service';
 
 export interface DropdownOption {
@@ -32,8 +34,7 @@ export interface DropdownOption {
     'aria-haspopup': 'listbox',
     '[attr.aria-expanded]': 'isOpen()',
     '[attr.aria-controls]': "isOpen() ? dropdownId + '-listbox' : null",
-    '[attr.aria-activedescendant]':
-      "isOpen() && focusedIndex() >= 0 ? dropdownId + '-option-' + focusedIndex() : null",
+    '[attr.aria-activedescendant]': 'ariaActiveDescendant()',
     '[attr.aria-label]': 'ariaLabel()',
     '[class.open]': 'isOpen()',
     tabindex: '0',
@@ -50,7 +51,9 @@ export interface DropdownOption {
 })
 export class Dropdown implements OnInit {
   translation = inject(TranslationService).translation;
+  private platformId = inject(PLATFORM_ID);
   searchInput = viewChild<ElementRef<HTMLElement>>('searchInput');
+  optionItems = viewChildren<ElementRef<HTMLElement>>('optionItem');
 
   options = input<Array<DropdownOption | string>>([]);
   placeholder = input<string>('Select an option');
@@ -64,6 +67,13 @@ export class Dropdown implements OnInit {
   inputFocusMode = signal(false);
   focusedIndex = signal(-1);
   searchQuery = signal('');
+  recreateKey = signal(0);
+
+  ariaActiveDescendant = computed(() => {
+    return this.isOpen() && this.focusedIndex() >= 0
+      ? this.dropdownId + '-option-' + this.focusedIndex()
+      : null;
+  });
 
   private static nextId = 0;
   private isLatestMouseDownInsideInput = false;
@@ -73,12 +83,31 @@ export class Dropdown implements OnInit {
   constructor(private element: ElementRef) {
     effect(() => this.filteredOptions());
 
+    effect(() => {
+      const index = this.focusedIndex();
+      const isDropdownOpen = this.isOpen();
+
+      if (isDropdownOpen && index >= 0) {
+        requestAnimationFrame(() => {
+          this.scrollToIndex(index);
+        })
+      }
+    });
+
     effect(() => {
       const isDropdownOpen = this.isOpen();
 
       if (!isDropdownOpen) {
         if (untracked(this.inputFocusMode)) this.inputFocusMode.set(false);
         this.searchQuery.set('');
+
+        const input = this.searchInput();
+        if (isPlatformBrowser(this.platformId) && input) {
+          let currentValue = untracked(this.normalizedOptions).find(
+            (o) => o.value === this.value(),
+          );
+          if (currentValue) input.nativeElement.innerText = currentValue.label;
+        }
       }
     });
   }
@@ -93,6 +122,17 @@ export class Dropdown implements OnInit {
     }
   }
 
+  private scrollToIndex(index: number) {
+    if (!isPlatformBrowser(this.platformId)) return;
+
+    const items = this.optionItems();
+    if (items[index]) {
+      items[index].nativeElement.scrollIntoView({
+        block: 'nearest',
+      });
+    }
+  }
+
   normalizedOptions = computed(() => {
     return this.options().map((opt) => {
       if (typeof opt === 'string') {
@@ -112,30 +152,25 @@ export class Dropdown implements OnInit {
     return opts.filter((o) => o.label.toLowerCase().normalize('NFKD').includes(query));
   });
 
-  initialInputText = computed<string>(() => {
-    let currentValue = this.normalizedOptions().find((o) => o.value === this.value())?.label;
-    return currentValue ? currentValue : "";
-  })
-
   toggle() {
     if (this.isLatestMouseDownInsideInput) {
       this.isLatestMouseDownInsideInput = false;
       return;
     }
 
-    this.isOpen.update((v) => !v);
     if (this.isOpen()) {
+      this.close();
+    } else {
+      this.isOpen.set(true);
       this.searchQuery.set('');
+      this.focusedIndex.set(this.normalizedOptions().findIndex((o) => o.value === this.value()));
 
-      const currentIndex = this.normalizedOptions().findIndex((o) => o.value === this.value());
-      this.focusedIndex.set(currentIndex);
-
-      setTimeout(() => {
+      requestAnimationFrame(() => {
         const searchInputElement = this.searchInput()!.nativeElement;
 
         searchInputElement.focus();
         this.setCursorToEnd(searchInputElement);
-      }, 0);
+      });
     }
   }
 
@@ -156,7 +191,13 @@ export class Dropdown implements OnInit {
   }
 
   close() {
+    const isFocusInside = this.element.nativeElement.contains(document.activeElement);
+    const isDropdownOpen = this.isOpen();
+
     this.isOpen.set(false);
+    if (isFocusInside) this.element.nativeElement.focus({ preventScroll: true });
+    if (isDropdownOpen) this.recreateKey.update((v) => (v + 1) % 65536);
+
     this.focusedIndex.set(-1);
   }
 
@@ -248,7 +289,8 @@ export class Dropdown implements OnInit {
   onDocumentClick(event: MouseEvent) {
     if (
       !this.element.nativeElement.contains(event.target) &&
-      !this.isLatestMouseDownInsideContainer
+      !this.isLatestMouseDownInsideContainer &&
+      this.isOpen()
     ) {
       this.close();
     }