chore: minor TS adjustments @W-20496487

packages/@lwc/aria-reflection/src/index.ts

@@ -57,7 +57,7 @@ const ARIA_PROPERTIES = [
     'ariaValueNow',
     'ariaValueText',
     'role',
-];
+] as const;
 
 for (const prop of ARIA_PROPERTIES) {
     const attribute = prop.replace(/^aria/, 'aria-').toLowerCase(); // e.g. ariaPosInSet => aria-posinset

packages/@lwc/compiler/src/index.ts

@@ -6,8 +6,8 @@
  */
 export { transform, transformSync } from './transformers/transformer';
 
-export { TransformResult } from './transformers/shared';
-export {
+export type { TransformResult } from './transformers/shared';
+export type {
     NormalizedTransformOptions,
     TransformOptions,
     StylesheetConfig,

packages/@lwc/engine-core/src/framework/wiring/index.ts

@@ -7,7 +7,7 @@
 
 export { createContextProviderWithRegister, createContextWatcher } from './context';
 
-export {
+export type {
     ConfigCallback,
     ConfigValue,
     ContextConsumer,

packages/@lwc/engine-server/src/types.ts

@@ -19,28 +19,28 @@ export const HostValueKey = Symbol('value');
 export const HostHostKey = Symbol('host');
 export const HostContextProvidersKey = Symbol('context-providers');
 
-export enum HostNodeType {
-    Text = 'text',
-    Comment = 'comment',
-    Raw = 'raw',
-    Element = 'element',
-    ShadowRoot = 'shadow-root',
-}
+export const HostNodeType = {
+    Text: 'text',
+    Comment: 'comment',
+    Raw: 'raw',
+    Element: 'element',
+    ShadowRoot: 'shadow-root',
+} as const;
 
 export interface HostText {
-    [HostTypeKey]: HostNodeType.Text;
+    [HostTypeKey]: typeof HostNodeType.Text;
     [HostParentKey]: HostElement | null;
     [HostValueKey]: string;
 }
 
 export interface HostComment {
-    [HostTypeKey]: HostNodeType.Comment;
+    [HostTypeKey]: typeof HostNodeType.Comment;
     [HostParentKey]: HostElement | null;
     [HostValueKey]: string;
 }
 
 export interface HostRaw {
-    [HostTypeKey]: HostNodeType.Raw;
+    [HostTypeKey]: typeof HostNodeType.Raw;
     [HostParentKey]: HostElement | null;
     [HostValueKey]: string;
 }
@@ -57,15 +57,15 @@ export interface HostAttribute {
 export type HostParentNode = HostElement | HostShadowRoot;
 
 export interface HostShadowRoot {
-    [HostTypeKey]: HostNodeType.ShadowRoot;
+    [HostTypeKey]: typeof HostNodeType.ShadowRoot;
     [HostChildrenKey]: HostChildNode[];
     mode: 'open' | 'closed';
     delegatesFocus: boolean;
     [HostHostKey]: HostElement;
 }
 
 export interface HostElement {
-    [HostTypeKey]: HostNodeType.Element;
+    [HostTypeKey]: typeof HostNodeType.Element;
     // tagName cannot be used as a public component property as it is
     // explicitly given only a getter, so it doesn't need to be a Symbol.
     tagName: string;

packages/@lwc/errors/src/compiler/error-info/compiler.ts

@@ -16,7 +16,7 @@ export const GENERIC_COMPILER_ERROR = {
     level: DiagnosticLevel.Error,
     strictLevel: DiagnosticLevel.Fatal,
     url: '',
-};
+} as const satisfies LWCErrorInfo;
 
 export const CompilerValidationErrors = {
     INVALID_COMPAT_PROPERTY: {

packages/@lwc/errors/src/compiler/errors.ts

@@ -9,7 +9,7 @@ import { CompilerError, getCodeFromError, getFilename, getLocation } from './uti
 import type { DiagnosticLevel, LWCErrorInfo } from '../shared/types';
 import type { CompilerDiagnosticOrigin, CompilerDiagnostic } from './utils';
 
-export { CompilerDiagnosticOrigin, CompilerDiagnostic, CompilerError } from './utils';
+export { type CompilerDiagnosticOrigin, type CompilerDiagnostic, CompilerError } from './utils';
 
 export * from './error-info';
 
@@ -98,7 +98,11 @@ export function generateCompilerError(
  * @param args Values used to fill the error message template.
  * @throws Throws a compiler error if the provided condition is falsy.
  */
-export function invariant(condition: boolean, errorInfo: LWCErrorInfo, args?: any[]) {
+export function invariant(
+    condition: boolean,
+    errorInfo: LWCErrorInfo,
+    args?: any[]
+): asserts condition {
     if (!condition) {
         throw generateCompilerError(errorInfo, {
             messageArgs: args,

packages/@lwc/errors/src/compiler/instrumentation.ts

@@ -10,12 +10,14 @@ import type { ErrorConfig } from './errors';
 /**
  * Pattern modeled after @lwc/engine-core's reporting.ts system
  */
-export enum CompilerMetrics {
-    LWCDynamicDirective = 'lwc-dynamic-directive',
-    LWCRenderModeDirective = 'lwc-render-mode-directive',
-    LWCSpreadDirective = 'lwc-spread-directive',
-    DynamicImportTransform = 'dynamic-import-transform',
-}
+export const CompilerMetrics = {
+    LWCDynamicDirective: 'lwc-dynamic-directive',
+    LWCRenderModeDirective: 'lwc-render-mode-directive',
+    LWCSpreadDirective: 'lwc-spread-directive',
+    DynamicImportTransform: 'dynamic-import-transform',
+} as const;
+
+export type CompilerMetrics = (typeof CompilerMetrics)[keyof typeof CompilerMetrics];
 
 export interface InstrumentationObject {
     log: (errorInfo: LWCErrorInfo, config: ErrorConfig) => void;

packages/@lwc/errors/src/compiler/utils.ts

@@ -31,7 +31,7 @@ export class CompilerError extends Error implements CompilerDiagnostic {
         message: string,
         filename?: string,
         location?: Location,
-        level = DiagnosticLevel.Error
+        level: DiagnosticLevel = DiagnosticLevel.Error
     ) {
         super(message);
 

packages/@lwc/errors/src/shared/types.ts

@@ -4,16 +4,18 @@
  * SPDX-License-Identifier: MIT
  * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT
  */
-export enum DiagnosticLevel {
+export const DiagnosticLevel = {
     /** Unexpected error, parsing error, bundling error */
-    Fatal = 0,
+    Fatal: 0,
     /** Linting error with error level, invalid external reference, invalid import, invalid transform */
-    Error = 1,
+    Error: 1,
     /** Linting error with warning level, usage of an API to be deprecated */
-    Warning = 2,
+    Warning: 2,
     /** Logging messages */
-    Log = 3,
-}
+    Log: 3,
+} as const;
+
+export type DiagnosticLevel = (typeof DiagnosticLevel)[keyof typeof DiagnosticLevel];
 
 export interface LWCErrorInfo {
     code: number;

packages/@lwc/module-resolver/src/index.ts

@@ -6,10 +6,10 @@
  */
 
 export { resolveModule } from './resolve-module';
-export {
+export { RegistryType } from './types';
+export type {
     ModuleResolverConfig,
     RegistryEntry,
-    RegistryType,
     ModuleRecord,
     AliasModuleRecord,
     DirModuleRecord,

packages/@lwc/module-resolver/src/types.ts

@@ -5,10 +5,12 @@
  * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT
  */
 
-export enum RegistryType {
-    alias = 'alias',
-    dir = 'dir',
-}
+export const RegistryType = {
+    alias: 'alias',
+    dir: 'dir',
+} as const;
+
+export type RegistryType = (typeof RegistryType)[keyof typeof RegistryType];
 
 export interface RegistryEntry {
     entry: string;

packages/@lwc/module-resolver/src/utils.ts

@@ -179,7 +179,7 @@ export function validateNpmAlias(
     exposed: string[],
     map: { [key: string]: string },
     opts: InnerResolverOptions
-) {
+): void {
     Object.keys(map).forEach((specifier) => {
         if (!exposed.includes(specifier)) {
             throw new LwcConfigError(

packages/@lwc/shared/src/api-version.ts

@@ -33,10 +33,10 @@ const allVersions = [
     APIVersion.V64_256_SUMMER_25,
     APIVersion.V65_258_WINTER_26,
     APIVersion.V66_260_SPRING_26,
-];
+] as const;
 const allVersionsSet = /*@__PURE__@*/ new Set(allVersions);
-export const LOWEST_API_VERSION = allVersions[0];
-export const HIGHEST_API_VERSION = allVersions[allVersions.length - 1];
+export const LOWEST_API_VERSION: APIVersion = allVersions[0];
+export const HIGHEST_API_VERSION: APIVersion = allVersions[allVersions.length - 1];
 
 /**
  *

packages/@lwc/shared/src/aria.ts

@@ -90,24 +90,20 @@ type AriaAttrToPropMap = {
     [Prop in AriaProperty as AriaPropToAttrMap[Prop]]: Prop;
 };
 
-const { AriaAttrNameToPropNameMap, AriaPropNameToAttrNameMap } = /*@__PURE__*/ (() => {
-    const AriaAttrNameToPropNameMap: AriaAttrToPropMap = create(null);
-    const AriaPropNameToAttrNameMap: AriaPropToAttrMap = create(null);
+const AriaAttrNameToPropNameMap: AriaAttrToPropMap = create(null);
+const AriaPropNameToAttrNameMap: AriaPropToAttrMap = create(null);
 
-    // Synthetic creation of all AOM property descriptors for Custom Elements
-    forEach.call(AriaPropertyNames, (propName) => {
-        const attrName = StringToLowerCase.call(
-            StringReplace.call(propName, /^aria/, () => 'aria-')
-        ) as AriaAttribute;
-        // These type assertions are because the map types are a 1:1 mapping of ariaX to aria-x.
-        // TypeScript knows we have one of ariaX | ariaY and one of aria-x | aria-y, and tries to
-        // prevent us from doing ariaX: aria-y, but we that it's safe.
-        (AriaAttrNameToPropNameMap[attrName] as AriaProperty) = propName;
-        (AriaPropNameToAttrNameMap[propName] as AriaAttribute) = attrName;
-    });
-
-    return { AriaAttrNameToPropNameMap, AriaPropNameToAttrNameMap };
-})();
+// Synthetic creation of all AOM property descriptors for Custom Elements
+forEach.call(AriaPropertyNames, (propName) => {
+    const attrName = StringToLowerCase.call(
+        StringReplace.call(propName, /^aria/, () => 'aria-')
+    ) as AriaAttribute;
+    // These type assertions are because the map types are a 1:1 mapping of ariaX to aria-x.
+    // TypeScript knows we have one of ariaX | ariaY and one of aria-x | aria-y, and tries to
+    // prevent us from doing ariaX: aria-y, but we that it's safe.
+    (AriaAttrNameToPropNameMap[attrName] as AriaProperty) = propName;
+    (AriaPropNameToAttrNameMap[propName] as AriaAttribute) = attrName;
+});
 
 /**
  *

packages/@lwc/shared/src/assert.ts

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: MIT
  * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT
  */
+
 /**
  *
  * @param value
@@ -31,7 +32,7 @@ export function isTrue(value: any, msg: string): asserts value {
  * @param value
  * @param msg
  */
-export function isFalse(value: any, msg: string) {
+export function isFalse(value: any, msg: string): void {
     if (value) {
         throw new Error(`Assert Violation: ${msg}`);
     }

packages/@lwc/shared/src/context.ts

@@ -30,23 +30,23 @@ export interface ContextBinding<C extends object> {
 
 let contextKeys: ContextKeys;
 
-export function setContextKeys(config: ContextKeys) {
+export function setContextKeys(config: ContextKeys): void {
     isFalse(contextKeys, '`setContextKeys` cannot be called more than once');
 
     contextKeys = config;
 }
 
-export function getContextKeys() {
+export function getContextKeys(): ContextKeys {
     return contextKeys;
 }
 
-export function setTrustedContextSet(context: WeakSet<object>) {
+export function setTrustedContextSet(context: WeakSet<object>): void {
     isFalse(trustedContext, 'Trusted Context Set is already set!');
 
     trustedContext = context;
 }
 
-export function addTrustedContext(contextParticipant: object) {
+export function addTrustedContext(contextParticipant: object): void {
     // This should be a no-op when the trustedSignals set isn't set by runtime
     trustedContext?.add(contextParticipant);
 }

packages/@lwc/shared/src/html-attributes.ts

@@ -98,7 +98,7 @@ export function isGlobalHtmlAttribute(attrName: string): boolean {
 }
 
 // These are HTML standard prop/attribute IDL mappings, but are not predictable based on camel/kebab-case conversion
-export const SPECIAL_PROPERTY_ATTRIBUTE_MAPPING = /*@__PURE__@*/ new Map([
+export const SPECIAL_PROPERTY_ATTRIBUTE_MAPPING: Map<string, string> = /*@__PURE__@*/ new Map([
     ['accessKey', 'accesskey'],
     ['readOnly', 'readonly'],
     ['tabIndex', 'tabindex'],
@@ -121,7 +121,7 @@ export const SPECIAL_PROPERTY_ATTRIBUTE_MAPPING = /*@__PURE__@*/ new Map([
 // descriptors for these properties are added from HTMLElement.prototype to
 // LightningElement.prototype. For SSR, in order to match CSR behavior, this
 // list is used to determine which attributes to reflect.
-export const REFLECTIVE_GLOBAL_PROPERTY_SET = /*@__PURE__@*/ new Set([
+export const REFLECTIVE_GLOBAL_PROPERTY_SET: Set<string> = /*@__PURE__@*/ new Set([
     'accessKey',
     'dir',
     'draggable',
@@ -203,7 +203,7 @@ export function kebabCaseToCamelCase(attrName: string): string {
  * Because the template will never call them. It'll always call the camel
  * cased version.
  */
-export const AMBIGUOUS_PROP_SET = /*@__PURE__@*/ new Map([
+export const AMBIGUOUS_PROP_SET: Map<string, string> = /*@__PURE__@*/ new Map([
     ['bgcolor', 'bgColor'],
     ['accesskey', 'accessKey'],
     ['contenteditable', 'contentEditable'],
@@ -217,4 +217,9 @@ export const AMBIGUOUS_PROP_SET = /*@__PURE__@*/ new Map([
  * by users on their components.
  * We throw for these.
  */
-export const DISALLOWED_PROP_SET = /*@__PURE__@*/ new Set(['is', 'class', 'slot', 'style']);
+export const DISALLOWED_PROP_SET: Set<string> = /*@__PURE__@*/ new Set([
+    'is',
+    'class',
+    'slot',
+    'style',
+]);

packages/@lwc/ssr-client-utils/src/index.ts

@@ -57,7 +57,7 @@ class StyleDeduplicator extends HTMLElement {
  * stylesheet.
  * It can also be implicitly invoked by importing `@lwc/ssr-client-utils/register-lwc-style` as a bare import.
  */
-export function registerLwcStyleComponent() {
+export function registerLwcStyleComponent(): void {
     customElements.define('lwc-style', StyleDeduplicator);
 }
 

packages/@lwc/ssr-runtime/src/index.ts

@@ -28,7 +28,7 @@ export { setFeatureFlag, setFeatureFlagForTest } from '@lwc/features';
 export { ClassList } from './class-list';
 export {
     LightningElement,
-    LightningElementConstructor,
+    type LightningElementConstructor,
     SYMBOL__DEFAULT_TEMPLATE,
     SYMBOL__GENERATE_MARKUP,
     SYMBOL__SET_INTERNALS,
@@ -37,7 +37,7 @@ export { mutationTracker } from './mutation-tracker';
 export {
     fallbackTmpl,
     fallbackTmplNoYield,
-    GenerateMarkupAsyncYield,
+    type GenerateMarkupAsyncYield,
     renderAttrs,
     renderAttrsNoYield,
     addSlottedContent,

packages/@lwc/template-compiler/src/index.ts

@@ -17,8 +17,8 @@ import type { CompilerDiagnostic } from '@lwc/errors';
 import type { Root, TemplateCompileResult, TemplateParseResult } from './shared/types';
 
 export * from './shared/types';
-export { CustomRendererConfig, CustomRendererElementConfig } from './shared/renderer-hooks';
-export { Config } from './config';
+export type { CustomRendererConfig, CustomRendererElementConfig } from './shared/renderer-hooks';
+export type { Config } from './config';
 export { toPropertyName } from './shared/utils';
 export { kebabcaseToCamelcase } from './shared/naming';
 export { generateScopeTokens } from './scopeTokens';

packages/@lwc/template-compiler/src/parser/index.ts

@@ -401,7 +401,7 @@ function parseLwcComponent(
         );
     }
 
-    return ast.lwcComponent(parse5Elm.tagName as LwcTagName.Component, parse5ElmLocation);
+    return ast.lwcComponent(parse5Elm.tagName as typeof LwcTagName.Component, parse5ElmLocation);
 }
 
 function parseLwcElementAsBuiltIn(