Can I use FormData API in plugin sandbox？

I’m going to assume you’re attempting to fetch data in code.ts. In this case, you’re trying to access browser APIs in a file that only knows about Figma APIs.

Try moving your logic to your UI file and then pass the response to code.ts via a postMessage.

Thanks you a lot. In dev mode codegen(recent supported by Figma) panel, sandbox can not communicate with ui.

Actually you can. Just call the invisible UI to access the Browser API.

When I called figma.showUI before, there was an error, thank you for your reply, I will try again.

Works!! figma.showUI can pass visible: false.

figma.showUI('xxx', { visible: false });