15. The driver ___on the brakes when a child ran in front of his car. A. slammed B. hit C... 17. If you have finished with those tools, I wish you’d ___ them ___. A. put/up B. put/do...

[最佳答案] This setup should work better for your needs: var req = new XMLHttpRequest(); req.open('POST', '/upload_image'); req.onreadystatechange = function (aEvt) { if (req.readyState == 4) { if(req.status == 200) alert(req.responseText); else alert("Error loading page\n"); } }; req.send(formData); In your code error callback is never called because it is only triggered by network-level errors, it ignores HTTP return codes.