chore(next): link/router/document missing types (#12692)

packages/next/client/link.tsx

@@ -11,7 +11,7 @@ import {
 import Router from './router'
 import { addBasePath } from '../next-server/lib/router/router'
 
-function isLocal(href: string) {
+function isLocal(href: string): boolean {
   const url = parse(href, false, true)
   const origin = parse(getLocationOrigin(), false, true)
 
@@ -40,7 +40,7 @@ function memoizedFormatUrl(formatFunc: (href: Url, as?: Url) => FormatResult) {
   }
 }
 
-function formatUrl(url: Url) {
+function formatUrl(url: Url): string {
   return url && typeof url === 'object' ? formatWithValidation(url) : url
 }
 
@@ -60,7 +60,7 @@ const IntersectionObserver =
   typeof window !== 'undefined' ? window.IntersectionObserver : null
 const prefetched: { [cacheKey: string]: boolean } = {}
 
-function getObserver() {
+function getObserver(): IntersectionObserver | undefined {
   // Return shared instance of IntersectionObserver if already created
   if (observer) {
     return observer
@@ -125,11 +125,11 @@ class Link extends Component<LinkProps> {
 
   cleanUpListeners = () => {}
 
-  componentWillUnmount() {
+  componentWillUnmount(): void {
     this.cleanUpListeners()
   }
 
-  getPaths() {
+  getPaths(): string[] {
     const { pathname } = window.location
     const { href: parsedHref, as: parsedAs } = this.formatUrls(
       this.props.href,
@@ -139,7 +139,7 @@ class Link extends Component<LinkProps> {
     return [resolvedHref, parsedAs ? resolve(pathname, parsedAs) : resolvedHref]
   }
 
-  handleRef(ref: Element) {
+  handleRef(ref: Element): void {
     if (this.p && IntersectionObserver && ref && ref.tagName) {
       this.cleanUpListeners()
 
@@ -167,7 +167,7 @@ class Link extends Component<LinkProps> {
     }
   })
 
-  linkClicked = (e: React.MouseEvent) => {
+  linkClicked = (e: React.MouseEvent): void => {
     const { nodeName, target } = e.currentTarget as HTMLAnchorElement
     if (
       nodeName === 'A' &&
@@ -212,7 +212,7 @@ class Link extends Component<LinkProps> {
     })
   }
 
-  prefetch(options?: PrefetchOptions) {
+  prefetch(options?: PrefetchOptions): void {
     if (!this.p || typeof window === 'undefined') return
     // Prefetch the JSON page if asked (only in the client)
     const paths = this.getPaths()

packages/next/client/router.ts

@@ -104,7 +104,7 @@ routerEvents.forEach(event => {
   })
 })
 
-function getRouter() {
+function getRouter(): Router {
   if (!singletonRouter.router) {
     const message =
       'No router instance found.\n' +
@@ -120,7 +120,7 @@ export default singletonRouter as SingletonRouter
 // Reexport the withRoute HOC
 export { default as withRouter } from './with-router'
 
-export function useRouter() {
+export function useRouter(): NextRouter {
   return React.useContext(RouterContext)
 }
 
@@ -131,7 +131,7 @@ export function useRouter() {
 // Create a router and assign it as the singleton instance.
 // This is used in client side when we are initilizing the app.
 // This should **not** use inside the server.
-export const createRouter = (...args: RouterArgs) => {
+export const createRouter = (...args: RouterArgs): Router => {
   singletonRouter.router = new Router(...args)
   singletonRouter.readyCallbacks.forEach(cb => cb())
   singletonRouter.readyCallbacks = []

packages/next/pages/_document.tsx

@@ -37,7 +37,7 @@ function dedupe(bundles: any[]): any[] {
   return kept
 }
 
-function getOptionalModernScriptVariant(path: string) {
+function getOptionalModernScriptVariant(path: string): string {
   if (process.env.__NEXT_MODERN_BUILD) {
     return path.replace(/\.js$/, '.module.js')
   }
@@ -626,7 +626,7 @@ export class NextScript extends Component<OriginProps> {
       ))
   }
 
-  static getInlineScriptSource(documentProps: DocumentProps) {
+  static getInlineScriptSource(documentProps: DocumentProps): string {
     const { __NEXT_DATA__ } = documentProps
     try {
       const data = JSON.stringify(__NEXT_DATA__)
@@ -821,11 +821,11 @@ export class NextScript extends Component<OriginProps> {
   }
 }
 
-function getAmpPath(ampPath: string, asPath: string) {
+function getAmpPath(ampPath: string, asPath: string): string {
   return ampPath || `${asPath}${asPath.includes('?') ? '&' : '?'}amp=1`
 }
 
-function getPageFile(page: string, buildId?: string) {
+function getPageFile(page: string, buildId?: string): string {
   const startingUrl = page === '/' ? '/index' : page
   return buildId ? `${startingUrl}.${buildId}.js` : `${startingUrl}.js`
 }