Request a file as the Blob type with asynchronous XMLHttpRequest in a document context. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS req.status is 200 PASS req.response.size is 4 PASS buffer is "PASS" PASS FAIL Set responseType before open(): Successful open: Failed: [object ProgressEvent] PASS req.status is 200 PASS req.response.size is 4 PASS buffer is "PASS" PASS FAIL Set responseType before send(): Successful Failed: [object ProgressEvent] PASS req.status is 200 PASS req.response.size is 4 PASS buffer is "PASS" PASS Set responseType in HEADERS_RECEIVED: Successful PASS successfullyParsed is true TEST COMPLETE