Chapter 199 · Omnibus Instrument Product Analytics
Subchapter 199.28
references/EXAMPLE-react-tanstack-router-code-based.mdMarkdown19 KBView on GitHub
Repository: https://github.com/PostHog/context-mill Path: basics/react-tanstack-router-code-based
This is a React and TanStack Router (opens in a new tab) example demonstrating PostHog integration with product analytics, session replay, and error tracking. This example uses code-based routing where routes are defined programmatically.
npm installCreate a .env file in the root directory:
VITE_PUBLIC_POSTHOG_PROJECT_TOKEN=your_posthog_project_token
VITE_PUBLIC_POSTHOG_HOST=https://us.i.posthog.comGet your PostHog project token from your PostHog project settings (opens in a new tab).
npm run devOpen http://localhost:3000 (opens in a new tab) with your browser to see the app.
src/
├── contexts/
│ └── AuthContext.tsx # Authentication context with PostHog integration
├── main.tsx # App entry point with all routes defined in code
├── reportWebVitals.ts # Performance monitoring
└── styles.css # Global stylesPostHog is initialized using PostHogProvider from @posthog/react. The provider wraps the entire app in the root route component:
import { PostHogProvider } from '@posthog/react'
import { createRootRoute } from '@tanstack/react-router'
const rootRoute = createRootRoute({
component: RootComponent,
})
function RootComponent() {
return (
<PostHogProvider
apiKey={import.meta.env.VITE_PUBLIC_POSTHOG_PROJECT_TOKEN!}
options={{
api_host: '/ingest',
ui_host: import.meta.env.VITE_PUBLIC_POSTHOG_HOST || 'https://us.posthog.com',
defaults: '2026-01-30',
capture_exceptions: true,
debug: import.meta.env.DEV,
}}
>
{/* your app */}
</PostHogProvider>
)
}import { usePostHog } from '@posthog/react'
const posthog = usePostHog()
posthog.identify(username, {
username: username,
})import { usePostHog } from '@posthog/react'
const posthog = usePostHog()
posthog.capture('burrito_considered', {
total_considerations: count,
username: username,
})posthog.captureException(error)This example uses TanStack Router with code-based routing. Key details:
main.tsx using createRoute() and createRootRoute()addChildren() methoduseNavigate() from @tanstack/react-routerimport.meta.env.VITE_*PostHogProvider from @posthog/react in root routeThis example demonstrates code-based routing, where routes are defined programmatically:
import { createRoute, createRootRoute, createRouter } from '@tanstack/react-router'
const rootRoute = createRootRoute({ component: RootComponent })
const indexRoute = createRoute({
getParentRoute: () => rootRoute,
path: '/',
component: Home,
})
const burritoRoute = createRoute({
getParentRoute: () => rootRoute,
path: '/burrito',
component: BurritoPage,
})
const routeTree = rootRoute.addChildren([indexRoute, burritoRoute])
const router = createRouter({ routeTree })For file-based routing (auto-generated from file structure), see the react-tanstack-router-file-based example.
VITE_PUBLIC_POSTHOG_PROJECT_TOKEN=<ph_project_token>
VITE_PUBLIC_POSTHOG_HOST=<ph_client_api_host>
package-lock.json
pnpm-lock.yaml
yarn.lock
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<link rel="icon" href="/favicon.ico" />
<meta name="theme-color" content="#000000" />
<meta
name="description"
content="React TanStack Router code-based routing example"
/>
<link rel="apple-touch-icon" href="/logo192.png" />
<link rel="manifest" href="/manifest.json" />
<title>React TanStack Router - Code-Based</title>
</head>
<body>
<div id="app"></div>
<script type="module" src="/src/main.tsx"></script>
</body>
</html>
// @ts-check
/** @type {import('prettier').Config} */
const config = {
semi: false,
singleQuote: true,
trailingComma: "all",
};
export default config;
# https://www.robotstxt.org/robotstxt.html
User-agent: *
Disallow:
import { createContext, useContext, useState, type ReactNode } from 'react';
import { usePostHog } from '@posthog/react';
interface User {
username: string;
burritoConsiderations: number;
}
interface AuthContextType {
user: User | null;
login: (username: string, password: string) => Promise<boolean>;
logout: () => void;
incrementBurritoConsiderations: () => void;
}
const AuthContext = createContext<AuthContextType | undefined>(undefined);
const users: Map<string, User> = new Map();
export function AuthProvider({ children }: { children: ReactNode }) {
// Use lazy initializer to read from localStorage only once on mount
const [user, setUser] = useState<User | null>(() => {
if (typeof window === 'undefined') return null;
const storedUsername = localStorage.getItem('currentUser');
if (storedUsername) {
const existingUser = users.get(storedUsername);
if (existingUser) {
return existingUser;
}
}
return null;
});
const posthog = usePostHog();
const login = async (username: string, password: string): Promise<boolean> => {
if (!username || !password) {
return false;
}
// Get or create user in local map
let user = users.get(username);
const isNewUser = !user;
if (!user) {
user = { username, burritoConsiderations: 0 };
users.set(username, user);
}
setUser(user);
localStorage.setItem('currentUser', username);
// Identify user in PostHog using username as distinct ID
posthog.identify(username, {
username: username,
isNewUser: isNewUser,
});
// Capture login event
posthog.capture('user_logged_in', {
username: username,
isNewUser: isNewUser,
});
return true;
};
const logout = () => {
// Capture logout event before resetting
posthog.capture('user_logged_out');
posthog.reset();
setUser(null);
localStorage.removeItem('currentUser');
};
const incrementBurritoConsiderations = () => {
if (user) {
user.burritoConsiderations++;
users.set(user.username, user);
setUser({ ...user });
}
};
return (
<AuthContext.Provider value={{ user, login, logout, incrementBurritoConsiderations }}>
{children}
</AuthContext.Provider>
);
}
export function useAuth() {
const context = useContext(AuthContext);
if (context === undefined) {
throw new Error('useAuth must be used within an AuthProvider');
}
return context;
}
import { StrictMode, useState } from 'react'
import ReactDOM from 'react-dom/client'
import {
Link,
Outlet,
RouterProvider,
createRootRoute,
createRoute,
createRouter,
useNavigate,
} from '@tanstack/react-router'
import { TanStackRouterDevtoolsPanel } from '@tanstack/react-router-devtools'
import { TanStackDevtools } from '@tanstack/react-devtools'
import { PostHogProvider, usePostHog } from '@posthog/react'
const reportWebVitals = (onPerfEntry?: () => void) => {
if (onPerfEntry && onPerfEntry instanceof Function) {
import('web-vitals').then(({ onCLS, onINP, onFCP, onLCP, onTTFB }) => {
onCLS(onPerfEntry)
onINP(onPerfEntry)
onFCP(onPerfEntry)
onLCP(onPerfEntry)
onTTFB(onPerfEntry)
})
}
}
export default reportWebVitals
import { defineConfig, loadEnv } from 'vite'
import viteReact from '@vitejs/plugin-react'
import tailwindcss from '@tailwindcss/vite'
import { fileURLToPath, URL } from 'node:url'
// https://vitejs.dev/config/
export default defineConfig(({ mode }) => {
const env = loadEnv(mode, process.cwd(), '')
return {
plugins: [viteReact(), tailwindcss()],
resolve: {
alias: {
'@': fileURLToPath(new URL('./src', import.meta.url)),
},
},
server: {
proxy: {
'/ingest': {
target: env.VITE_PUBLIC_POSTHOG_HOST || 'https://us.i.posthog.com',
changeOrigin: true,
rewrite: (path) => path.replace(/^\/ingest/, ''),
},
},
},
}
})