---
url: /reference/OutputOptions.manualChunks.md
---
# ~~manualChunks~~

* **Type**: (`moduleId`, `meta`) => `string` | `undefined` | `null` | `void`
* **Optional**

Allows you to do manual chunking. Provided for Rollup compatibility.

You could use this option for migration purpose. Under the hood,

```js
{
  manualChunks: (moduleId, meta) => {
    if (moduleId.includes('node_modules')) {
      return 'vendor';
    }
    return null;
  }
}
```

will be transformed to

```js
{
  codeSplitting: {
    groups: [
      {
        name(moduleId) {
          if (moduleId.includes('node_modules')) {
            return 'vendor';
          }
          return null;
        },
      },
    ],
  }
}

```

Note that unlike Rollup, object form is not supported.

## Parameters

### moduleId

`string`

### meta

#### getModuleInfo

(`moduleId`) => [`ModuleInfo`](Interface.ModuleInfo.md) | `null`

## Returns

`string` | `undefined` | `null` | `void`

## Deprecated

Please use [`output.codeSplitting`](./OutputOptions.codeSplitting) instead.

:::warning
If `manualChunks` and `codeSplitting` are both specified, `manualChunks` option will be ignored.
:::