> For AI agents: the complete documentation index is available at /llms.txt, the full documentation bundle is available at /llms-full.txt.

# HotModuleReplacementPlugin

Enables hot module replacement (HMR).

## Examples

Enabling HMR is straightforward and in most cases no options are necessary.

Note that HMR can not be used in production build. You can use `process.env.NODE_ENV` to determine if it is a development environment.

```js title="rspack.config.mjs"
import { rspack } from '@rspack/core';
const isDev = process.env.NODE_ENV === 'development';

export default {
  plugins: [isDev && new rspack.HotModuleReplacementPlugin()],
};
```

## Runtime API

When you register the `HotModuleReplacementPlugin` plugin, Rspack will inject HMR related runtime APIs, such as `module.hot` and `import.meta.webpackHot`.

See [HMR API](/api/runtime-api/hmr.md) for more details.

## React Fast Refresh

To enable Fast Refresh in React projects, you also need to use the [@rspack/plugin-react-refresh](https://www.npmjs.com/package/@rspack/plugin-react-refresh) plugin.

See [React - Fast Refresh](/guide/integrations/react.md#fast-refresh) for more details.

## Preact Fast Refresh

To enable Fast Refresh in Preact projects, you also need to use the [@rspack/plugin-preact-refresh](https://www.npmjs.com/package/@rspack/plugin-preact-refresh) plugin.

See [Preact - Fast Refresh](/guide/integrations/preact.md#preact-refresh) for more details.