Does this proxy came with caching functionality?

[nnnikolay]

I see that the proxy server sends if-none-match HTTP header, which my API server handles as a key to check, was the data changed or not. Which is totally fine. But there is a problem: the proxy server receives 304 HTTP status code and empty body which makes sense. But, in that case, my browser doesn't get the data from the proxy server at all.
Is there any way to fix that? except this one

proxy.on('proxyReq', (proxyReq) => {
  proxyReq.setHeader('X-API-Key', config.api.key);
  proxyReq.setHeader("if-none-match", "");
});