refactor on button states

src/app/components/tabview/tabview.ts

@@ -35,7 +35,6 @@ import { Subscription } from 'rxjs';
 import { TabViewChangeEvent, TabViewCloseEvent } from './tabview.interface';
 import { UniqueComponentId } from 'primeng/utils';
 import { Nullable } from 'primeng/ts-helpers';
-import { AnimationStyleMetadata } from '@angular/animations';
 
 /**
  * TabPanel is a helper component for TabView component.
@@ -496,6 +495,7 @@ export class TabView implements AfterContentInit, AfterViewChecked, OnDestroy, B
 
         this.tabChangesSubscription = (this.tabPanels as QueryList<TabPanel>).changes.subscribe((_) => {
             this.initTabs();
+            this.refreshButtonState();
         });
 
         (this.templates as QueryList<PrimeTemplate>).forEach((item) => {
@@ -524,7 +524,7 @@ export class TabView implements AfterContentInit, AfterViewChecked, OnDestroy, B
         this.list = DomHandler.findSingle(this.el.nativeElement, '[data-pc-section="nav"]');
 
         this.resizeObserver = new ResizeObserver(() => {
-            if (this.list.offsetWidth > this.container.offsetWidth) {
+            if (this.list.offsetWidth >= this.container.offsetWidth) {
                 this.buttonVisible = true;
             } else {
                 this.buttonVisible = false;
@@ -812,6 +812,20 @@ export class TabView implements AfterContentInit, AfterViewChecked, OnDestroy, B
         this.forwardIsDisabled = scrollLeft === scrollWidth - width;
     }
 
+    refreshButtonState() {
+        this.container = DomHandler.findSingle(this.el.nativeElement, '[data-pc-section="navcontent"]');
+        this.list = DomHandler.findSingle(this.el.nativeElement, '[data-pc-section="nav"]');
+        if (this.list.offsetWidth >= this.container.offsetWidth) {
+            if (this.list.offsetWidth >= this.container.offsetWidth) {
+                this.buttonVisible = true;
+            } else {
+                this.buttonVisible = false;
+            }
+            this.updateButtonState();
+            this.cd.markForCheck();
+        }
+    }
+
     onScroll(event: Event) {
         this.scrollable && this.updateButtonState();