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

# tools.tsChecker

- **Type:** `Object | Function`
- **Default:**

```js
const defaultOptions = {
  typescript: {
    // set 'readonly' to avoid emitting tsbuildinfo,
    // as the generated tsbuildinfo will break ts-checker-rspack-plugin
    mode: 'readonly',
    // enable build when using project reference
    build: useReference,
    // avoid OOM issue
    memoryLimit: 8192,
    // use tsconfig of user project
    configFile: tsconfigPath,
    // resolve the default TypeScript package from user project
    resolveRoot: rootPath,
  },
  issue: {
    // ignore type errors from node_modules
    exclude: [({ file = '' }) => /[\\/]node_modules[\\/]/.test(file)],
  },
  logger: {
    log() {
      // do nothing
      // we only want to display error messages
    },
    error(message: string) {
      console.error(
        message
          .replace(/ERROR/g, 'Type Error')
          .replace(/WARNING/g, 'Type Warning'),
      );
    },
  },
},
```

By default, the [@rsbuild/plugin-type-check](https://github.com/rstackjs/rsbuild-plugin-type-check) is enabled for type checking. You can use `output.disableTsChecker` config to disable it.

## Example

### Object Type

When the value of `tsChecker` is an object, it will be deeply merged with the default configuration.

```ts
export default {
  tools: {
    tsChecker: {
      issue: {
        exclude: [({ file = '' }) => /[\\/]some-folder[\\/]/.test(file)],
      },
    },
  },
};
```

### Function Type

When the value of `tsChecker` is a function, the default configuration will be passed as the first argument. You can directly modify the configuration object or return an object as the final configuration.

```ts
export default {
  tools: {
    tsChecker(options) {
      options.async = false;
      return options;
    },
  },
};
```

> Please refer to [@rsbuild/plugin-type-check](https://github.com/rstackjs/rsbuild-plugin-type-check) for more details.

## TypeScript 7+ Support

`tools.tsChecker` supports the native checker included in TypeScript 7+. This capability is provided by [`ts-checker-rspack-plugin`](https://github.com/rstackjs/ts-checker-rspack-plugin), which is integrated by [`@rsbuild/plugin-type-check`](https://github.com/rstackjs/rsbuild-plugin-type-check), and can reduce type-checking time on large projects.

Install TypeScript >= 7.0.0 to enable `tsgo` automatically:


```sh [npm]
npm install typescript@latest -D
```

```sh [yarn]
yarn add typescript@latest -D
```

```sh [pnpm]
pnpm add typescript@latest -D
```

```sh [bun]
bun add typescript@latest -D
```

```sh [deno]
deno add npm:typescript@latest -D
```

When `tsgo` is enabled and `typescript.typescriptPath` is set manually, it must point to an absolute TypeScript 7+ `typescript/package.json` path or the legacy `@typescript/native-preview/package.json` path.

> The `@typescript/native-preview` path is kept only for compatibility. New setups should use TypeScript 7+ from the standard `typescript` package.

For supported options and limitations, please refer to [ts-checker-rspack-plugin - TypeScript 7+ support](https://github.com/rstackjs/ts-checker-rspack-plugin#typescript-7-support).