About esbuild-register's banner

How do I set the `banner` property of esbuild in this code:

```
spawn(`node`, ['--loader', 'esbuild-register/loader', '-r', 'esbuild-register', '. /src/index.ts'], {
      stdio: 'inherit'
    }).
```

Trying to achieve the same effect as the following:

```
register({
    banner: 'console.log('****')'
  }).
```

@egoist 