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# Core Utilities
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Essential utilities for rendering, element creation, and DOM integration. These provide the foundation for React Native Web's compatibility layer.
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## Rendering
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### render
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Renders a React Native Web application to a DOM container. This is the primary entry point for web applications.
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```javascript { .api }
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function render(
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  element: React.Element,
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  container: DOMContainer,
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  callback?: Function
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): void;
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```
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**Parameters:**
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- `element` - The React element to render
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- `container` - DOM element to render into
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- `callback` - Optional callback called after render
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**Usage:**
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```javascript
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import { AppRegistry } from "react-native-web";
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AppRegistry.registerComponent("App", () => App);
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AppRegistry.runApplication("App", {
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  rootTag: document.getElementById("root"),
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});
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```
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### unmountComponentAtNode
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Unmounts a React Native Web component from a DOM container.
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```javascript { .api }
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function unmountComponentAtNode(container: DOMContainer): boolean;
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```
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**Parameters:**
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- `container` - DOM container to unmount from
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**Returns:** `boolean` - true if component was unmounted
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## DOM Integration
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### findNodeHandle
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Returns the DOM node handle for a React Native component reference. Used for measuring and DOM operations.
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```javascript { .api }
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function findNodeHandle(componentOrHandle: any): number | null;
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```
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**Parameters:**
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- `componentOrHandle` - React component reference or existing handle
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**Returns:** `number | null` - DOM node handle or null
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**Usage:**
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```javascript
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const viewRef = useRef();
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const nodeHandle = findNodeHandle(viewRef.current);
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```
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### unstable_createElement
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Low-level element creation utility with React Native compatibility. Handles style, event, and prop normalization for web.
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```javascript { .api }
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function unstable_createElement(
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  type: string,
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  props?: Object,
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  ...children: any[]
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): React.Element;
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```
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**Parameters:**
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- `type` - Element type (string or component)
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- `props` - Element properties
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- `children` - Child elements
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**Returns:** `React.Element` - Created React element
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*Note: This is an unstable API and may change in future versions.*
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## Color Processing
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### processColor
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Processes and normalizes color values to web-compatible formats. Handles React Native color formats and converts them for web use.
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```javascript { .api }
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function processColor(color: ColorValue): string | null;
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```
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**Parameters:**
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- `color` - Color value (string, number, or null)
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**Returns:** `string | null` - Processed CSS color string or null
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**Usage:**
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```javascript
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const webColor = processColor('#FF0000'); // Returns '#FF0000'
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const webColor2 = processColor('red'); // Returns 'red'
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const webColor3 = processColor(0xFF0000); // Returns '#ff0000'
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```
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## Native Modules
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### NativeModules
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Empty object for React Native compatibility. Maintains API compatibility with React Native but contains no modules on web.
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```javascript { .api }
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const NativeModules: {};
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```
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This is provided for compatibility with React Native code that may reference `NativeModules`, but will be empty on web platforms.