feat(language-service): Add support for idle timeout in defer blocks

SkyZeroZx · thePunderWoman · commit c6f98c723cdd · 2026-03-04T07:57:30.000-08:00
Extends language service parsing and validation to support `@defer on idle(300)`
diff --git a/packages/language-service/src/quick_info_built_ins.ts b/packages/language-service/src/quick_info_built_ins.ts
@@ -170,7 +170,8 @@ const BUILT_IN_NAMES_TO_DOC_MAP: {
     displayInfoKind: DisplayInfoKind.KEYWORD,
   },
   'idle': {
-    docString: triggerDescriptionPreamble + `the browser reports idle state (default).`,
+    docString:
+      triggerDescriptionPreamble + `the browser reports idle state. Accepts an optional timeout.`,
     links: ['[Reference](https://angular.dev/guide/templates/defer#on-idle)'],
     displayInfoKind: DisplayInfoKind.TRIGGER,
   },
diff --git a/packages/language-service/test/grp3/quick_info_spec.ts b/packages/language-service/test/grp3/quick_info_spec.ts
@@ -734,6 +734,14 @@ describe('quick info', () => {
             });
           });
 
+          it('idle with timeout', () => {
+            expectQuickInfo({
+              templateOverride: `@defer (on i¦dle(500ms)) { } `,
+              expectedSpanText: 'idle',
+              expectedDisplayString: '(trigger) idle',
+            });
+          });
+
           it('hover', () => {
             expectQuickInfo({
               templateOverride: `@defer (on hov¦er(x)) { } <div #x></div> `,
diff --git a/packages/language-service/test/legacy/template_target_spec.ts b/packages/language-service/test/legacy/template_target_spec.ts
@@ -42,6 +42,7 @@ import {
   TmplAstSwitchExhaustiveCheck as SwitchExhaustiveCheck,
   TmplAstTemplate as Template,
   TmplAstTextAttribute as TextAttribute,
+  TmplAstIdleDeferredTrigger as IdleDeferredTrigger,
   TmplAstTimerDeferredTrigger as TimerDeferredTrigger,
   TmplAstVariable as Variable,
 } from '@angular/compiler';
@@ -1239,6 +1240,15 @@ describe('blocks', () => {
     expect((node as TimerDeferredTrigger).delay).toBe(2000);
   });
 
+  it('should visit idle on conditions on defer blocks with timeout', () => {
+    const {nodes, position} = parse(` @defer (on idle(5¦00ms)) { } `);
+    const {context} = getTargetAtPosition(nodes, position)!;
+    const {node} = context as SingleNodeTarget;
+    expect(isTemplateNode(node!)).toBe(true);
+    expect(node).toBeInstanceOf(IdleDeferredTrigger);
+    expect((node as IdleDeferredTrigger).timeout).toBe(500);
+  });
+
   // TODO: Should the parser ingest a property read for `localRef`, instead of a string?
   // (Talk to Kristiyan?)
   // xit('should visit on conditions on defer blocks', () => {
