# TypeScript

Start with the [gRPC guide](../grpc.md) to create a Platform API token and download `platform.proto`. Run the commands below from the directory containing that file.

Browsers cannot open native gRPC HTTP/2 connections. The Platform API also accepts [gRPC-Web](https://github.com/grpc/grpc-web) on its HTTP/1.1 endpoint. Install `protoc`, the `protoc-gen-js` and `protoc-gen-grpc-web` plugins, and the runtime packages:

```bash
npm install grpc-web google-protobuf
npm install --save-dev @types/google-protobuf
mkdir -p src/generated
protoc -I. platform.proto \
  --js_out=import_style=commonjs,binary:src/generated \
  --grpc-web_out=import_style=typescript,mode=grpcweb:src/generated
```

Download the compiler plugins from the [official gRPC-Web releases and setup guide](https://github.com/grpc/grpc-web#code-generator-plugins); they must be on your `PATH`. The command generates `platform_pb.js`, its TypeScript declarations, and `PlatformServiceClientPb.ts`.

```typescript
import {PlatformServicePromiseClient} from './generated/PlatformServiceClientPb';
import {GetCatalogRequest, ListCatalogsRequest} from './generated/platform_pb';

// Supply a token at runtime. Do not bundle a long-lived API token in browser code.
export async function listCatalogDetails(token: string) {
  const client = new PlatformServicePromiseClient('https://reconstruct.dev');
  const metadata = {authorization: `Bearer ${token}`};
  const listRequest = new ListCatalogsRequest();
  listRequest.setPageSize(10);

  const page = await client.listCatalogs(listRequest, metadata);
  for (const catalog of page.getCatalogsList()) {
    const detailRequest = new GetCatalogRequest();
    detailRequest.setCatalogId(catalog.getCatalogId());
    const detail = await client.getCatalog(detailRequest, metadata);
    console.log(detail.getCatalogId(), detail.getDescription());
  }
}
```

For a browser app, the public API must allow that app's origin through CORS. Keep persistent API tokens on a trusted server; a browser bundle cannot protect an embedded secret.