Function isHtmlResponse

isHtmlResponse(response: unknown): response is Response

Type guard to validate if a Response object contains HTML content. Checks both the Content-Type header and ensures it's a valid Response object.

Parameters

response: unknown
The Response object to validate

Returns response is Response

Type predicate indicating if the response contains HTML content

Example

// Valid HTML response
const htmlResponse = new Response('<html><body>Hello</body></html>', {
  headers: { 'Content-Type': 'text/html' }
});
if (isHtmlResponse(htmlResponse)) {
  const text = await htmlResponse.text();
  console.log('HTML content:', text);
}

// Non-HTML response
const jsonResponse = new Response('{"data": "test"}', {
  headers: { 'Content-Type': 'application/json' }
});
if (!isHtmlResponse(jsonResponse)) {
  console.log('Not an HTML response');
}

Source

export function isHtmlResponse(response: unknown): response is Response {
  if (!isHttpResponse(response)) return false;
  const contentType = response.headers.get("Content-Type");
  return (
    contentType !== null &&
    (contentType.includes("text/") ||
      contentType.includes("application/xhtml+xml") ||
      contentType.includes("json-amazonui-streaming"))
  );
}