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

# output.filenameHash

- **Type:**

```ts
type FilenameHash =
  | boolean
  | string
  | {
      enable?: boolean | 'always';
      format?: string;
    };
```

- **Default:** `true`

Configure whether to add a hash value to output filenames.

You can use the following formats:

- `true`: JavaScript and CSS filenames include hash in production mode for web targets, while other assets always include hash in all modes.
- `false`: Disable filename hash.
- `string`: Enable filename hash and customize the hash format, such as `'contenthash:16'`.
- `object`: Configure `enable` and `format` separately. `enable` controls whether to add filename hash; `format` sets the hash format.

If [output.filename](/config/output/filename.md) is configured, it has a higher priority than `output.filenameHash`.

### Disable hash

By default, output file names include a hash value:

```bash
dist/static/css/index.7879e19dab.css
dist/static/js/index.18a568e5ab.js
```

You can set `output.filenameHash` to `false` to disable this behavior:

```ts title="rsbuild.config.ts"
export default {
  output: {
    filenameHash: false,
  },
};
```

After rebuilding, the output filenames become:

```bash
dist/static/css/index.css
dist/static/js/index.js
```

### Hash format

The default hash format is `contenthash:10`, which generates a 10-character hash based on the content of the file.

You can set `output.filenameHash` to other formats supported by Rspack and customize the length.

```ts title="rsbuild.config.ts"
export default {
  output: {
    filenameHash: 'contenthash:16',
  },
};
```

The optional hash formats are:

- `contenthash` (recommended): The hash value of the file content. The hash value will only change when the content of the file itself changes.
- `chunkhash`: The hash value of the chunk. The hash value will only change when the content of the chunk (and its included modules) changes.
- `fullhash`: The hash value of the entire compilation. If any file changes, the hash values of all output files in the entire project will change.

You can also configure the hash format using an object:

```ts title="rsbuild.config.ts"
export default {
  output: {
    filenameHash: {
      format: 'contenthash:16',
    },
  },
};
```

### Always enable hash

By default, JavaScript and CSS filenames include hash only in production mode for web targets, and do not include hash in development builds. When `output.target` is not `web`, JavaScript bundle filenames do not include hash by default, such as Node.js bundles.

If you need JavaScript and CSS filenames to always include hash, set `filenameHash.enable` to `'always'`. This also applies to development builds and Node.js bundles.

```ts title="rsbuild.config.ts"
export default {
  output: {
    filenameHash: {
      enable: 'always',
    },
  },
};
```

:::tip
Enabling filename hash in development mode may cause HMR to fail, especially for CSS files.
:::

## Version history

| Version | Changes                                  |
| ------- | ---------------------------------------- |
| v2.0.0  | Default hash length changed from 8 to 10 |
| v2.0.4  | Added support for the object format      |