从Javascript上传文件

Question

I'm developing a Javascript app and I need to use the Mediafire REST API to upload a file. (See upload ducmentation here ).

Following this MDN tutorial , and some research, I've written the code below, but it seems it's not working... Note that I don't need for the moment to control the progress and so on, I only want to do the most basic upload operation possible...

Also note that I could a different code, and even jQuery or other (free) libraries, so if you have a better code to upload a file I'd be really grateful...

var controller = this;
var file = $("#file").get(0).files[0];
//The file is correctly retrieved here...

var xhr = new XMLHttpRequest();
xhr.open('POST', 'http://www.mediafire.com/api/upload/upload.php?session_token=' + controller.sessionToken.token);
//(The session_token is valid)
xhr.overrideMimeType('text/plain; charset=x-user-defined');
xhr.setRequestHeader('x-filesize', file.size);

var reader = new FileReader();
reader.onload = function (evt) {
  var uInt8Array = new Uint8Array(evt.target.result);
  //It seems that here the ArrayBuffer is read correctly, 
  //and I converted it to a ArrayBufferView because Chrome suggested it...
  xhr.send(uInt8Array);
};
reader.readAsArrayBuffer(file);

I can't tell the concrete error, I only know that nothing is happens... but maybe looking at the code you can see some obvious error... The only thing I see is this in Chrome's console:

Note: I know the quality of this question is not the desired and it's TOO vague, but I tried to do my best taking into account that I'm completely new to ALL these technologies...

Answer 1

The presence of an OPTIONS request and the presence of specific headers in the OPTIONS request indicates that your POST request is a cross-domain request. The user agent, following the CORS spec , is first sending an OPTIONS request. This is also called a preflight request, and it is sent, in your case, due to the non-standard header you are including (x-filesize) and the fact that the Content-Type is not form-encoded, MPE, or text/plain. You can either deal with the OPTIONS request server-side, or make appropriate changes to your request so that a preflight is not required. Either way, you are going to have to deal with CORS requests server-side since you are apparently making a cross-domain request. You can read more about CORS in this excellent MDN article .

PS Why are you using FileReader here? Just send the File object via XHR, or, better yet, append the File to a FormData object and send that.