use-dom

What are DOM Components?

DOM components allow web code to run verbatim in a webview on native platforms while rendering as-is on web. This enables using web-only libraries like recharts, react-syntax-highlighter, or any React web library in your Expo app without modification.

When to Use DOM Components

Use DOM components when you need:

• Web-only libraries — Charts (recharts, chart.js), syntax highlighters, rich text editors, or any library that depends on DOM APIs
• Migrating web code — Bring existing React web components to native without rewriting
• Complex HTML/CSS layouts — When CSS features aren't available in React Native
• iframes or embeds — Embedding external content that requires a browser context (embed only trusted origins, use the iframe sandbox attribute with a restrictive allow list, and place remote or third-party embeds in a separate DOM component that receives only plain data props and no native action props)
• Canvas or WebGL — Web graphics APIs not available natively

When NOT to Use DOM Components

Avoid DOM components when:

• Native performance is critical — Webviews add overhead
• Simple UI — React Native components are more efficient for basic layouts
• Deep native integration — Use local modules instead for native APIs
• Layout routes — _layout files cannot be DOM components

Basic DOM Component

Create a new file with the 'use dom'; directive at the top:

// components/WebChart.tsx
"use dom";

export default function WebChart({
  data,
}: {
  data: number[];
  dom: import("expo/dom").DOMProps;
}) {
  return (
    <div style={{ padding: 20 }}>
      <h2>Chart Data</h2>
      <ul>
        {data.map((value, i) => (
          <li key={i}>{value}</li>
        ))}
      </ul>
    </div>
  );
}

Rules for DOM Components

1. Must have 'use dom'; directive at the top of the file
2. Single default export — One React component per file
3. Own file — Cannot be defined inline or combined with native components
4. Serializable props only — Strings, numbers, booleans, arrays, plain objects. Async function props are the supported exception: they become bridge calls, and their arguments and return values must be serializable
5. Include CSS in the component file — DOM components run in isolated context

The dom Prop

Every DOM component receives a special dom prop for webview configuration. Always type it in your props (marking it optional is also valid, since callers often omit it):

"use dom";

interface Props {
  content: string;
  dom: import("expo/dom").DOMProps;
}

export default function MyComponent({ content }: Props) {
  return <div>{content}</div>;
}

Common dom Prop Options

// Disable body scrolling
<DOMComponent dom={{ scrollEnabled: false }} />

// Flow under the notch (disable safe area insets)
<DOMComponent dom={{ contentInsetAdjustmentBehavior: "never" }} />

// Control size manually
<DOMComponent dom={{ style: { width: 300, height: 400 } }} />

// Combine options
<DOMComponent
  dom={{
    scrollEnabled: false,
    contentInsetAdjustmentBehavior: "never",
    style: { width: '100%', height: 500 }
  }}
/>

Exposing Native Actions to the Webview

Pass async functions as props to expose native functionality to the DOM component:

// app/index.tsx (native)
import { Alert } from "react-native";
import DOMComponent from "@/components/dom-component";

export default function Screen() {
  return (
    <DOMComponent
      showAlert={async (message: string) => {
        Alert.alert("From Web", message);
      }}
      saveData={async (data: { name: string; value: number }) => {
        // Save to native storage, database, etc.
        console.log("Saving:", data);
        return { success: true };
      }}
    />
  );
}

// components/dom-component.tsx
"use dom";

interface Props {
  showAlert: (message: string) => Promise<void>;
  saveData: (data: {
    name: string;
    value: number;
  }) => Promise<{ success: boolean }>;
  dom?: import("expo/dom").DOMProps;
}

export default function DOMComponent({ showAlert, saveData }: Props) {
  const handleClick = async () => {
    await showAlert("Hello from the webview!");
    const result = await saveData({ name: "test", value: 42 });
    console.log("Save result:", result);
  };

  return <button onClick={handleClick}>Trigger Native Action</button>;
}

Treat every call from the webview as untrusted input: any script running in the DOM component, including third-party libraries, can call these functions with any arguments. In the native handler, check the type, range and length of each argument before acting, and reject unexpected values. Keep bridged functions small and narrowly scoped to the specific action the component needs, rather than general storage, database, file or command functions.

Using Web Libraries

DOM components can use any web library. Prefer well maintained, vetted packages, pin versions with a committed lockfile, and install from the official npm registry. Remember that library code in a DOM component can call every function prop passed to it.

Examples:

// components/syntax-highlight.tsx
"use dom";

import SyntaxHighlighter from "react-syntax-highlighter";
import { docco } from "react-syntax-highlighter/dist/esm/styles/hljs";

interface Props {
  code: string;
  language: string;
  dom?: import("expo/dom").DOMProps;
}

export default function SyntaxHighlight({ code, language }: Props) {
  return (
    <SyntaxHighlighter language={language} style={docco}>
      {code}
    </SyntaxHighlighter>
  );
}

// components/chart.tsx
"use dom";

import {
  LineChart,
  Line,
  XAxis,
  YAxis,
  CartesianGrid,
  Tooltip,
} from "recharts";

interface Props {
  data: Array<{ name: string; value: number }>;
  dom: import("expo/dom").DOMProps;
}

export default function Chart({ data }: Props) {
  return (
    <LineChart width={400} height={300} data={data}>
      <CartesianGrid strokeDasharray="3 3" />
      <XAxis dataKey="name" />
      <YAxis />
      <Tooltip />
      <Line type="monotone" dataKey="value" stroke="#8884d8" />
    </LineChart>
  );
}

CSS in DOM Components

CSS imports must be in the DOM component file since they run in isolated context:

// components/styled-component.tsx
"use dom";

import "@/styles.css";

export default function StyledComponent({
  dom,
}: {
  dom: import("expo/dom").DOMProps;
}) {
  return (
    <div className="container">
      <h1 className="title">Styled Content</h1>
    </div>
  );
}

The at sign alias resolves from the project root configured for the app, not from the component folder.

Or use inline styles / CSS-in-JS:

"use dom";

const styles = {
  container: {
    padding: 20,
    backgroundColor: "#f0f0f0",
  },
  title: {
    fontSize: 24,
    color: "#333",
  },
};

export default function StyledComponent({
  dom,
}: {
  dom: import("expo/dom").DOMProps;
}) {
  return (
    <div style={styles.container}>
      <h1 style={styles.title}>Styled Content</h1>
    </div>
  );
}

Expo Router in DOM Components

The expo-router <Link /> component and router API work inside DOM components:

"use dom";

import { Link, useRouter } from "expo-router";

export default function Navigation({
  dom,
}: {
  dom: import("expo/dom").DOMProps;
}) {
  const router = useRouter();

  return (
    <nav>
      <Link href="/about">About</Link>
      <button onClick={() => router.push("/settings")}>Settings</button>
    </nav>
  );
}

Router APIs That Require Props

These hooks don't work directly in DOM components because they need synchronous access to native routing state:

• useLocalSearchParams()
• useGlobalSearchParams()
• usePathname()
• useSegments()
• useRootNavigation()
• useRootNavigationState()

Solution: Read these values in the native parent and pass as props:

// app/[id].tsx (native)
import { useLocalSearchParams, usePathname } from "expo-router";
import DOMComponent from "@/components/dom-component";

export default function Screen() {
  const { id } = useLocalSearchParams();
  const pathname = usePathname();

  return <DOMComponent id={id as string} pathname={pathname} />;
}

// components/dom-component.tsx
"use dom";

interface Props {
  id: string;
  pathname: string;
  dom?: import("expo/dom").DOMProps;
}

export default function DOMComponent({ id, pathname }: Props) {
  return (
    <div>
      <p>Current ID: {id}</p>
      <p>Current Path: {pathname}</p>
    </div>
  );
}

Detecting DOM Environment

Check if code is running in a DOM component:

"use dom";

import { IS_DOM } from "expo/dom";

export default function Component({
  dom,
}: {
  dom?: import("expo/dom").DOMProps;
}) {
  return <div>{IS_DOM ? "Running in DOM component" : "Running natively"}</div>;
}

Inside a use dom file, IS_DOM is false only when the component renders on web, so the false branch in this example runs on web rather than natively.

Assets

Prefer requiring assets instead of using the public directory:

"use dom";

// Good - bundled with the component
const logo = require("../assets/logo.png");

export default function Component({
  dom,
}: {
  dom: import("expo/dom").DOMProps;
}) {
  return <img src={logo} alt="Logo" />;
}

Usage from Native Components

Import and use DOM components like regular components:

// app/index.tsx
import { View, Text } from "react-native";
import WebChart from "@/components/web-chart";
import CodeBlock from "@/components/code-block";

export default function HomeScreen() {
  return (
    <View style={{ flex: 1 }}>
      <Text>Native content above</Text>

      <WebChart data={[10, 20, 30, 40, 50]} dom={{ style: { height: 300 } }} />

      <CodeBlock
        code="const x = 1;"
        language="javascript"
        dom={{ scrollEnabled: true }}
      />

      <Text>Native content below</Text>
    </View>
  );
}

Platform Behavior

On web, the dom prop is ignored since no webview is needed.

On iOS and Android, install the React Native webview package in the project before using DOM components.

Tips

• DOM components hot reload during development
• Keep DOM components focused — don't put entire screens in webviews
• Use native components for navigation chrome, DOM components for specialized content
• Test on all platforms — web rendering may differ slightly from native webviews
• Large DOM components may impact performance — profile if needed
• The webview has its own JavaScript context — cannot directly share state with native
• Keep secrets, auth tokens and other sensitive data in native code and out of DOM component props, since props are copied into the webview context where third-party code runs; expose only narrowly scoped async actions instead