Response Handling

var uploader = new MultipleUpload(el, {
 uploadUrl: '/api/upload',
 responseParser: function(xhr) {
 // Parse custom server response format
 try {
 var data = JSON.parse(xhr.responseText);
 return {
 success: data.status === 'ok',
 fileId: data.id,
 url: data.downloadUrl,
 message: data.message || ''
 };
 } catch (e) {
 return { success: false, message: 'Invalid server response' };
 }
 },
 onTaskComplete: function(task) {
 console.log('File ID:', task.response.fileId);
 console.log('Download URL:', task.response.url);
 }
});

Your API's shape, not the component's

responseParser pulls the fields you need out of whatever your endpoint returns, so a server already speaking its own JSON dialect does not have to change to match the uploader. Extract the URL, the id, the storage key — whatever the rest of your application needs.

Errors are the half that gets skipped

A failed upload usually carries a useful message in the body, and without a parser the user sees a bare status code. Pulling your API's error text through here is the difference between “HTTP 422” and “that document type is not accepted for this case”.