fix(multiple): use DI token for tag name (#30892)

Reads the tag name through DI, instead of going through the DOM which should be more SSR-friendly.

Author: crisbeto

src/cdk-experimental/combobox/combobox.ts

@@ -23,6 +23,7 @@ import {
   Directive,
   ElementRef,
   EventEmitter,
+  HOST_TAG_NAME,
   InjectionToken,
   Injector,
   Input,
@@ -60,6 +61,7 @@ export const CDK_COMBOBOX = new InjectionToken<CdkCombobox>('CDK_COMBOBOX');
   providers: [{provide: CDK_COMBOBOX, useExisting: CdkCombobox}],
 })
 export class CdkCombobox<T = unknown> implements OnDestroy {
+  private readonly _tagName = inject(HOST_TAG_NAME);
   private readonly _elementRef = inject<ElementRef<HTMLElement>>(ElementRef);
   private readonly _overlay = inject(Overlay);
   protected readonly _viewContainerRef = inject(ViewContainerRef);
@@ -245,8 +247,8 @@ export class CdkCombobox<T = unknown> implements OnDestroy {
 
   private _isTextTrigger() {
     // TODO: Should check if the trigger is contenteditable.
-    const tagName = this._elementRef.nativeElement.tagName.toLowerCase();
-    return tagName === 'input' || tagName === 'textarea' ? true : false;
+    const tagName = this._tagName.toLowerCase();
+    return tagName === 'input' || tagName === 'textarea';
   }
 
   private _getOverlayConfig() {

src/material/badge/badge.ts

@@ -21,6 +21,7 @@ import {
   OnInit,
   Renderer2,
   ViewEncapsulation,
+  HOST_TAG_NAME,
 } from '@angular/core';
 import {_animationsDisabled, ThemePalette} from '../core';
 import {_CdkPrivateStyleLoader, _VisuallyHiddenLoader} from '@angular/cdk/private';
@@ -156,15 +157,18 @@ export class MatBadge implements OnInit, OnDestroy {
 
     if (typeof ngDevMode === 'undefined' || ngDevMode) {
       const nativeElement = this._elementRef.nativeElement;
+
       if (nativeElement.nodeType !== nativeElement.ELEMENT_NODE) {
         throw Error('matBadge must be attached to an element node.');
       }
 
+      const tagName = inject(HOST_TAG_NAME);
+
       // Heads-up for developers to avoid putting matBadge on <mat-icon>
       // as it is aria-hidden by default docs mention this at:
       // https://material.angular.io/components/badge/overview#accessibility
       if (
-        nativeElement.tagName.toLowerCase() === 'mat-icon' &&
+        tagName.toLowerCase() === 'mat-icon' &&
         nativeElement.getAttribute('aria-hidden') === 'true'
       ) {
         console.warn(

src/material/chips/chip.ts

@@ -21,6 +21,7 @@ import {
   DoCheck,
   ElementRef,
   EventEmitter,
+  HOST_TAG_NAME,
   Injector,
   Input,
   NgZone,
@@ -90,6 +91,7 @@ export interface MatChipEvent {
 export class MatChip implements OnInit, AfterViewInit, AfterContentInit, DoCheck, OnDestroy {
   _changeDetectorRef = inject(ChangeDetectorRef);
   _elementRef = inject<ElementRef<HTMLElement>>(ElementRef);
+  private readonly _tagName = inject(HOST_TAG_NAME);
   protected _ngZone = inject(NgZone);
   private _focusMonitor = inject(FocusMonitor);
   private _globalRippleOptions = inject<RippleGlobalOptions>(MAT_RIPPLE_GLOBAL_OPTIONS, {
@@ -256,10 +258,9 @@ export class MatChip implements OnInit, AfterViewInit, AfterContentInit, DoCheck
   ngOnInit() {
     // This check needs to happen in `ngOnInit` so the overridden value of
     // `basicChipAttrName` coming from base classes can be picked up.
-    const element = this._elementRef.nativeElement;
     this._isBasicChip =
-      element.hasAttribute(this.basicChipAttrName) ||
-      element.tagName.toLowerCase() === this.basicChipAttrName;
+      this._elementRef.nativeElement.hasAttribute(this.basicChipAttrName) ||
+      this._tagName.toLowerCase() === this.basicChipAttrName;
   }
 
   ngAfterViewInit() {