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Corrupted .xlsx file from Flask web app and ajax POST request

I have a Flask web app with a URL route that receives a post request with some json, parses it to an .xlsx file, then returns the file with send_file().
Server side, I can see that the .xlsx file that is generated is correct but, once downloaded on the client side, the file is corrupted and can't be opened and is much larger than expected (201KB vs. 112KB).
I suspect it's some sort of encoding issue, but I've tried a whole bunch of stuff and can't make any headway. Can anyone help, please?
Flask route:
#app.route('/request/export_XLSX',methods=['POST'])
def request_export_XLSX():
json_model = json_util.loads(request.data.decode('ascii', 'ignore'))
xlsx_model = detox.xlsxFromJSONModel(json_model) # Returns file path
result = send_file(xlsx_model, as_attachment=True, attachment_filename=json_model['id']+'.xlsx', mimetype='application/vnd.ms-excel')
return result
JavaScript:
var exportModelExcel = function(){
var model = detox.fba.model
d3.selectAll('*').style("cursor","wait")
var modelJson = JSON.stringify(model)
$.ajax({
type: "POST",
url: "/request/export_XLSX",
data: modelJson,
success: function(d){
d3.selectAll('*').style("cursor","")
var blob = new Blob([d], {type: 'application/vnd.ms-excel'})
var link=document.createElement("a");
link.href=window.URL.createObjectURL(blob);
link.download=model.id+".xlsx";
link.click();
},
error: function(jqxhr,textStatus,errorThrown){
console.log("Error: " ,textStatus,errorThrown)
d3.selectAll('*').style("cursor","")
alert("There was an error exporting the model")
},
contentType: 'application/json',
responseType: 'blob',
processData: false,
});
}
Here's a link where you can see the good and bad .xlsx files: https://gofile.io/d/xywI1D

Well, I ended up ripping out the ajax and using an XMLHTTPRequest instead.
It works nicely and results in an uncorrupted .xlsx file. 🙂
var exportModelExcel = function(){
var model = detox.fba.model;
var modelJson = JSON.stringify(model);
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
var downloadUrl = URL.createObjectURL(xhttp.response);
var a = document.createElement("a");
document.body.appendChild(a);
a.style = "display: none";
a.href = downloadUrl;
a.download = model.id+".xlsx";
a.click();
}
};
xhttp.open("POST", "/request/export_XLSX", true);
xhttp.setRequestHeader("Content-Type", "application/json");
xhttp.responseType = "blob";
xhttp.send(modelJson);
}

Safari Issue : Downloaded file name is "Unknown" Javascript

I have converted my existing data to text/csv and able to download the file in Chrome but when tried with Safari on iPad or Mac it opens a tab with name "unknown"/ "Untitled" . This is the code I am using -
var hiddenElement = document.createElement('a');
hiddenElement.href = 'data:text/csv,'+ encodeURI(response);
hiddenElement.target = '_blank';
hiddenElement.download = 'purchase.csv';
hiddenElement.click();
Is there anyway I can able to show the downloaded file as "purchase.csv" for safari.

Try this one
var a = document.createElement('a');
a.setAttribute("href",URL);
a.setAttribute("target", "_blank");
var dispatch = document.createEvent("HTMLEvents");
dispatch.initEvent("click", true, true);
a.dispatchEvent(dispatch);
return false;

IF the data is LOCAL -- Easy!
We just use window.URL.createObjectURL(). Let's set some globals...
//var response = Already defined by OP! Not sure what it is, but it's data to save.
var mimetype = "text/csv";
var filename = "purchase.csv";
Now we just set the header by means of the type argument to window.URL.createObjectURL()...
a.href = window.URL.createObjectURL(new Blob([response], {
encoding: "UTF-8",
type: mimetype + ";charset=UTF-8",
}));
IF the data is on the WEB -- Still easy, just more effort!
We can do this by means of XMLHTTPRequest() to download the file data, window.URL.createObjectURL() to cast the data to a blob type with MIME type headers, and then proceed normally in setting a.download = filename; and a.click();.
An abstract function for download file data directly to the JavaScript environment...
function load(url, callback) {
var xhr = new XMLHTTPRequest();
xhr.onreadystatechange = function () {
if (xhr.readyState === 4 && xhr.status === 200) callback(xhr.responseText);
};
xhr.open("GET", url, true);
}
Then download the data, build the link, and click it:
load("site.com/t.txt", function (contents) {
var a = window.document.createElement('a');
a.href = window.URL.createObjectURL(new Blob([response], {
encoding: "UTF-8",
type: mimetype + ";charset=UTF-8",
}));
a.download = filename;
document.body.appendChild(a);
a.click();
a.remove();
});

Downloading file from ajax result using blob

I use this code to download excel file from server.
$.ajax({
headers: CLIENT.authorize(),
url: '/server/url',
type: 'POST',
contentType: "application/json; charset=utf-8",
data: JSON.stringify(jsonData),
success: function (data) {
alert('Data size: ' + data.length);
var blob = new Blob([data], { type: "application/vnd.ms-excel" });
alert('BLOB SIZE: ' + data.length);
var URL = window.URL || window.webkitURL;
var downloadUrl = URL.createObjectURL(blob);
document.location = downloadUrl;
},
});
The problem I experience is that even though data and blob sizes are identical, the moment document.location gets assigned I'm prompted to download almoste two times larger excel file. And when I try to open it, excel complains about wrong file format and opened file contains a lot of garbage, even though required text is still there.
Any ideas what is causing this and how to avoid it?

So I solved the problem using AJAX 2. It natively supports binary streams. You can't use jQuery for that, unless you base64 encode everything, apparently.
Working code looks like this:
var xhr = new XMLHttpRequest();
xhr.open('POST', '/le/url', true);
xhr.responseType = 'blob';
$.each(SERVER.authorization(), function(k, v) {
xhr.setRequestHeader(k, v);
});
xhr.setRequestHeader('Content-type', 'application/json; charset=utf-8');
xhr.onload = function(e) {
preloader.modal('hide');
if (this.status == 200) {
var blob = new Blob([this.response], {type: 'application/vnd.ms-excel'});
var downloadUrl = URL.createObjectURL(blob);
var a = document.createElement("a");
a.href = downloadUrl;
a.download = "data.xls";
document.body.appendChild(a);
a.click();
} else {
alert('Unable to download excel.')
}
};
xhr.send(JSON.stringify(jsonData));
Hope this helps.

download file using an ajax request

I want to send an "ajax download request" when I click on a button, so I tried in this way:
javascript:
var xhr = new XMLHttpRequest();
xhr.open("GET", "download.php");
xhr.send();
download.php:
<?
header("Cache-Control: public");
header("Content-Description: File Transfer");
header("Content-Disposition: attachment; filename= file.txt");
header("Content-Transfer-Encoding: binary");
readfile("file.txt");
?>
but doesn't work as expected, how can I do ? Thank you in advance

Update April 27, 2015
Up and coming to the HTML5 scene is the download attribute. It's supported in Firefox and Chrome, and soon to come to IE11. Depending on your needs, you could use it instead of an AJAX request (or using window.location) so long as the file you want to download is on the same origin as your site.
You could always make the AJAX request/window.location a fallback by using some JavaScript to test if download is supported and if not, switching it to call window.location.
Original answer
You can't have an AJAX request open the download prompt since you physically have to navigate to the file to prompt for download. Instead, you could use a success function to navigate to download.php. This will open the download prompt but won't change the current page.
$.ajax({
url: 'download.php',
type: 'POST',
success: function() {
window.location = 'download.php';
}
});
Even though this answers the question, it's better to just use window.location and avoid the AJAX request entirely.

To make the browser downloads a file you need to make the request like that:
function downloadFile(urlToSend) {
var req = new XMLHttpRequest();
req.open("GET", urlToSend, true);
req.responseType = "blob";
req.onload = function (event) {
var blob = req.response;
var fileName = req.getResponseHeader("fileName") //if you have the fileName header available
var link=document.createElement('a');
link.href=window.URL.createObjectURL(blob);
link.download=fileName;
link.click();
};
req.send();
}

You actually don't need ajax at all for this. If you just set "download.php" as the href on the button, or, if it's not a link use:
window.location = 'download.php';
The browser should recognise the binary download and not load the actual page but just serve the file as a download.

Cross browser solution, tested on Chrome, Firefox, Edge, IE11.
In the DOM, add an hidden link tag:
<a id="target" style="display: none"></a>
Then:
var req = new XMLHttpRequest();
req.open("GET", downloadUrl, true);
req.responseType = "blob";
req.setRequestHeader('my-custom-header', 'custom-value'); // adding some headers (if needed)
req.onload = function (event) {
var blob = req.response;
var fileName = null;
var contentType = req.getResponseHeader("content-type");
// IE/EDGE seems not returning some response header
if (req.getResponseHeader("content-disposition")) {
var contentDisposition = req.getResponseHeader("content-disposition");
fileName = contentDisposition.substring(contentDisposition.indexOf("=")+1);
} else {
fileName = "unnamed." + contentType.substring(contentType.indexOf("/")+1);
}
if (window.navigator.msSaveOrOpenBlob) {
// Internet Explorer
window.navigator.msSaveOrOpenBlob(new Blob([blob], {type: contentType}), fileName);
} else {
var el = document.getElementById("target");
el.href = window.URL.createObjectURL(blob);
el.download = fileName;
el.click();
}
};
req.send();

It is possible. You can have the download started from inside an ajax function, for example, just after the .csv file is created.
I have an ajax function that exports a database of contacts to a .csv file, and just after it finishes, it automatically starts the .csv file download. So, after I get the responseText and everything is Ok, I redirect browser like this:
window.location="download.php?filename=export.csv";
My download.php file looks like this:
<?php
$file = $_GET['filename'];
header("Cache-Control: public");
header("Content-Description: File Transfer");
header("Content-Disposition: attachment; filename=".$file."");
header("Content-Transfer-Encoding: binary");
header("Content-Type: binary/octet-stream");
readfile($file);
?>
There is no page refresh whatsoever and the file automatically starts downloading.
NOTE - Tested in the following browsers:
Chrome v37.0.2062.120
Firefox v32.0.1
Opera v12.17
Internet Explorer v11

I prefer location.assign(url);
Complete syntax example:
document.location.assign('https://www.urltodocument.com/document.pdf');
developer.mozilla.org/en-US/docs/Web/API/Location.assign

For those looking a more modern approach, you can use the fetch API. The following example shows how to download a spreadsheet file. It is easily done with the following code.
fetch(url, {
body: JSON.stringify(data),
method: 'POST',
headers: {
'Content-Type': 'application/json; charset=utf-8'
},
})
.then(response => response.blob())
.then(response => {
const blob = new Blob([response], {type: 'application/application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'});
const downloadUrl = URL.createObjectURL(blob);
const a = document.createElement("a");
a.href = downloadUrl;
a.download = "file.xlsx";
document.body.appendChild(a);
a.click();
})
I believe this approach to be much easier to understand than other XMLHttpRequest solutions. Also, it has a similar syntax to the jQuery approach, without the need to add any additional libraries.
Of course, I would advise checking to which browser you are developing, since this new approach won't work on IE. You can find the full browser compatibility list on the following link.
Important: In this example I am sending a JSON request to a server listening on the given url. This url must be set, on my example I am assuming you know this part. Also, consider the headers needed for your request to work. Since I am sending a JSON, I must add the Content-Type header and set it to application/json; charset=utf-8, as to let the server know the type of request it will receive.

#Joao Marcos solution works for me but I had to modify the code to make it work on IE, below if what the code looks like
downloadFile(url,filename) {
var that = this;
const extension = url.split('/').pop().split('?')[0].split('.').pop();
var req = new XMLHttpRequest();
req.open("GET", url, true);
req.responseType = "blob";
req.onload = function (event) {
const fileName = `${filename}.${extension}`;
const blob = req.response;
if (window.navigator.msSaveBlob) { // IE
window.navigator.msSaveOrOpenBlob(blob, fileName);
}
const link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
link.download = fileName;
link.click();
URL.revokeObjectURL(link.href);
};
req.send();
},

Decoding a filename from the header is a little bit more complex...
var filename = "default.pdf";
var disposition = req.getResponseHeader('Content-Disposition');
if (disposition && disposition.indexOf('attachment') !== -1)
{
var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
var matches = filenameRegex.exec(disposition);
if (matches != null && matches[1])
filename = matches[1].replace(/['"]/g, '');
}

This solution is not very different from those above, but for me it works very well and i think it's clean.
I suggest to base64 encode the file server side (base64_encode(), if you are using PHP) and send the base64 encoded data to the client
On the client you do this:
let blob = this.dataURItoBlob(THE_MIME_TYPE + "," + response.file);
let uri = URL.createObjectURL(blob);
let link = document.createElement("a");
link.download = THE_FILE_NAME,
link.href = uri;
document.body.appendChild(link);
link.click();
document.body.removeChild(link);
This code puts the encoded data in a link and simulates a click on the link, then it removes it.

Your needs are covered by
window.location('download.php');
But I think that you need to pass the file to be downloaded, not always download the same file, and that's why you are using a request, one option is to create a php file as simple as showfile.php and do a request like
var myfile = filetodownload.txt
var url = "shofile.php?file=" + myfile ;
ajaxRequest.open("GET", url, true);
showfile.php
<?php
$file = $_GET["file"]
echo $file;
where file is the file name passed via Get or Post in the request and then catch the response in a function simply
if(ajaxRequest.readyState == 4){
var file = ajaxRequest.responseText;
window.location = 'downfile.php?file=' + file;
}
}

there is another solution to download a web page in ajax. But I am referring to a page that must first be processed and then downloaded.
First you need to separate the page processing from the results download.
1) Only the page calculations are made in the ajax call.
$.post("CalculusPage.php", { calculusFunction: true, ID: 29, data1: "a", data2: "b" },
function(data, status)
{
if (status == "success")
{
/* 2) In the answer the page that uses the previous calculations is downloaded. For example, this can be a page that prints the results of a table calculated in the ajax call. */
window.location.href = DownloadPage.php+"?ID="+29;
}
}
);
// For example: in the CalculusPage.php
if ( !empty($_POST["calculusFunction"]) )
{
$ID = $_POST["ID"];
$query = "INSERT INTO ExamplePage (data1, data2) VALUES ('".$_POST["data1"]."', '".$_POST["data2"]."') WHERE id = ".$ID;
...
}
// For example: in the DownloadPage.php
$ID = $_GET["ID"];
$sede = "SELECT * FROM ExamplePage WHERE id = ".$ID;
...
$filename="Export_Data.xls";
header("Content-Type: application/vnd.ms-excel");
header("Content-Disposition: inline; filename=$filename");
...
I hope this solution can be useful for many, as it was for me.

this works for me
var dataObj = {
somekey:"someValue"
}
$.ajax({
method: "POST",
url: "/someController/someMethod",
data: dataObj,
success: function (response) {
const blob = new Blob([response], { type: 'text/csv' });
const downloadUrl = URL.createObjectURL(blob);
const a = document.createElement("a");
a.href = downloadUrl;
a.download = "file.csv";
document.body.appendChild(a);
a.click();
}
});

Download and open PDF file using Ajax

I have an action class that generates a PDF. The contentType is set appropriately.
public class MyAction extends ActionSupport
{
public String execute() {
...
...
File report = signedPdfExporter.generateReport(xyzData, props);
inputStream = new FileInputStream(report);
contentDisposition = "attachment=\"" + report.getName() + "\"";
contentType = "application/pdf";
return SUCCESS;
}
}
I call this action through an Ajax call. I don't know the way to deliver this stream to browser. I tried a few things but nothing worked.
$.ajax({
type: "POST",
url: url,
data: wireIdList,
cache: false,
success: function(response)
{
alert('got response');
window.open(response);
},
error: function (XMLHttpRequest, textStatus, errorThrown)
{
alert('Error occurred while opening fax template'
+ getAjaxErrorString(textStatus, errorThrown));
}
});
The above gives the error:
Your browser sent a request that this server could not understand.

Here is how I got this working
$.ajax({
url: '<URL_TO_FILE>',
success: function(data) {
var blob=new Blob([data]);
var link=document.createElement('a');
link.href=window.URL.createObjectURL(blob);
link.download="<FILENAME_TO_SAVE_WITH_EXTENSION>";
link.click();
}
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
Updated answer using download.js
$.ajax({
url: '<URL_TO_FILE>',
success: download.bind(true, "<FILENAME_TO_SAVE_WITH_EXTENSION>", "<FILE_MIME_TYPE>")
});

You don't necessarily need Ajax for this. Just an <a> link is enough if you set the content-disposition to attachment in the server side code. This way the parent page will just stay open, if that was your major concern (why would you unnecessarily have chosen Ajax for this otherwise?). Besides, there is no way to handle this nicely acynchronously. PDF is not character data. It's binary data. You can't do stuff like $(element).load(). You want to use completely new request for this. For that pdf is perfectly suitable.
To assist you more with the server side code, you'll need to tell more about the language used and post an excerpt of the code attempts.

I don't really think that any of the past answers spotted out the problem of the original poster. They all presume a GET request while the poster was trying to POST data and get a download in response.
In the course of searching for any better answer we found this jQuery Plugin for Requesting Ajax-like File Downloads (if link is broken sometime in the future, see the internet archive).
In its "heart" it creates a "temporary" HTML form containing the given data as input fields. This form is appended to the document and posted to the desired URL. Right after that the form is removed again:
jQuery('<form action="'+ url +'" method="'+ (method||'post') +'">'+inputs+'</form>')
.appendTo('body').submit().remove()
Update Mayur's answer looks pretty promising and very simple in comparison to the jQuery plug-in I referred to.

This is how i solve this issue.
The answer of Jonathan Amend on this post helped me a lot.
The example below is simplified.
For more details, the above source code is able to download a file using a JQuery Ajax request (GET, POST, PUT etc). It, also, helps to upload parameters as JSON and to change the content type to application/json (my default).
The html source:
<form method="POST">
<input type="text" name="startDate"/>
<input type="text" name="endDate"/>
<input type="text" name="startDate"/>
<select name="reportTimeDetail">
<option value="1">1</option>
</select>
<button type="submit"> Submit</button>
</form>
A simple form with two input text, one select and a button element.
The javascript page source:
<script type="text/javascript" src="JQuery 1.11.0 link"></script>
<script type="text/javascript">
// File Download on form submition.
$(document).on("ready", function(){
$("form button").on("click", function (event) {
event.stopPropagation(); // Do not propagate the event.
// Create an object that will manage to download the file.
new AjaxDownloadFile({
url: "url that returns a file",
data: JSON.stringify($("form").serializeObject())
});
return false; // Do not submit the form.
});
});
</script>
A simple event on button click. It creates an AjaxDownloadFile object. The AjaxDownloadFile class source is below.
The AjaxDownloadFile class source:
var AjaxDownloadFile = function (configurationSettings) {
// Standard settings.
this.settings = {
// JQuery AJAX default attributes.
url: "",
type: "POST",
headers: {
"Content-Type": "application/json; charset=UTF-8"
},
data: {},
// Custom events.
onSuccessStart: function (response, status, xhr, self) {
},
onSuccessFinish: function (response, status, xhr, self, filename) {
},
onErrorOccured: function (response, status, xhr, self) {
}
};
this.download = function () {
var self = this;
$.ajax({
type: this.settings.type,
url: this.settings.url,
headers: this.settings.headers,
data: this.settings.data,
success: function (response, status, xhr) {
// Start custom event.
self.settings.onSuccessStart(response, status, xhr, self);
// Check if a filename is existing on the response headers.
var filename = "";
var disposition = xhr.getResponseHeader("Content-Disposition");
if (disposition && disposition.indexOf("attachment") !== -1) {
var filenameRegex = /filename[^;=\n]*=(([""]).*?\2|[^;\n]*)/;
var matches = filenameRegex.exec(disposition);
if (matches != null && matches[1])
filename = matches[1].replace(/[""]/g, "");
}
var type = xhr.getResponseHeader("Content-Type");
var blob = new Blob([response], {type: type});
if (typeof window.navigator.msSaveBlob !== "undefined") {
// IE workaround for "HTML7007: One or more blob URLs were revoked by closing the blob for which they were created. These URLs will no longer resolve as the data backing the URL has been freed.
window.navigator.msSaveBlob(blob, filename);
} else {
var URL = window.URL || window.webkitURL;
var downloadUrl = URL.createObjectURL(blob);
if (filename) {
// Use HTML5 a[download] attribute to specify filename.
var a = document.createElement("a");
// Safari doesn"t support this yet.
if (typeof a.download === "undefined") {
window.location = downloadUrl;
} else {
a.href = downloadUrl;
a.download = filename;
document.body.appendChild(a);
a.click();
}
} else {
window.location = downloadUrl;
}
setTimeout(function () {
URL.revokeObjectURL(downloadUrl);
}, 100); // Cleanup
}
// Final custom event.
self.settings.onSuccessFinish(response, status, xhr, self, filename);
},
error: function (response, status, xhr) {
// Custom event to handle the error.
self.settings.onErrorOccured(response, status, xhr, self);
}
});
};
// Constructor.
{
// Merge settings.
$.extend(this.settings, configurationSettings);
// Make the request.
this.download();
}
};
I created this class to added to my JS library. It is reusable. Hope that helps.

What worked for me is the following code, as the server function is retrieving File(memoryStream.GetBuffer(), "application/pdf", "fileName.pdf");:
$http.get( fullUrl, { responseType: 'arraybuffer' })
.success(function (response) {
var blob = new Blob([response], { type: 'application/pdf' });
if (window.navigator && window.navigator.msSaveOrOpenBlob) {
window.navigator.msSaveOrOpenBlob(blob); // for IE
}
else {
var fileURL = URL.createObjectURL(blob);
var newWin = window.open(fileURL);
newWin.focus();
newWin.reload();
}
});

To fix the blank PDF issue in post request to get stream data like PDF, we need to add response type as 'arraybuffer' or 'blob' in request
$.ajax({
url: '<URL>',
type: "POST",
dataType: 'arraybuffer',
success: function(data) {
let blob = new Blob([data], {type: 'arraybuffer'});
let link = document.createElement('a');
let objectURL = window.URL.createObjectURL(blob);
link.href = objectURL;
link.target = '_self';
link.download = "fileName.pdf";
(document.body || document.documentElement).appendChild(link);
link.click();
setTimeout(()=>{
window.URL.revokeObjectURL(objectURL);
link.remove();
}, 100);
}
});

You could use this plugin which creates a form, and submits it, then removes it from the page.
jQuery.download = function(url, data, method) {
//url and data options required
if (url && data) {
//data can be string of parameters or array/object
data = typeof data == 'string' ? data : jQuery.param(data);
//split params into form inputs
var inputs = '';
jQuery.each(data.split('&'), function() {
var pair = this.split('=');
inputs += '<input type="hidden" name="' + pair[0] +
'" value="' + pair[1] + '" />';
});
//send request
jQuery('<form action="' + url +
'" method="' + (method || 'post') + '">' + inputs + '</form>')
.appendTo('body').submit().remove();
};
};
$.download(
'/export.php',
'filename=mySpreadsheet&format=xls&content=' + spreadsheetData
);
This worked for me. Found this plugin here

Concerning the answer given by Mayur Padshala this is the correct logic to download a pdf file via ajax but as others report in the comments this solution is indeed downloads a blank pdf.
The reason for this is explained in the accepted answer of this question: jQuery has some issues loading binary data using AJAX requests, as it does not yet implement some HTML5 XHR v2 capabilities, see this enhancement request and this discussion.
So using HTMLHTTPRequest the code should look like this:
var req = new XMLHttpRequest();
req.open("POST", "URL", true);
req.responseType = "blob";
req.onload = function (event) {
var blob = req.response;
var link=document.createElement('a');
link.href=window.URL.createObjectURL(blob);
link.download="name_for_the_file_to_save_with_extention";
link.click();
}

The following code worked for me
//Parameter to be passed
var data = 'reportid=R3823&isSQL=1&filter=[]';
var xhr = new XMLHttpRequest();
xhr.open("POST", "Reporting.jsp"); //url.It can pdf file path
xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhr.responseType = "blob";
xhr.onload = function () {
if (this.status === 200) {
var blob = new Blob([xhr.response]);
const url = window.URL.createObjectURL(blob);
var a = document.createElement('a');
a.href = url;
a.download = 'myFile.pdf';
a.click();
setTimeout(function () {
// For Firefox it is necessary to delay revoking the ObjectURL
window.URL.revokeObjectURL(data)
, 100
})
}
};
xhr.send(data);

Hope this will save you a few hours and spare you from a headache.
It took me a while to figure this out, but doing regular $.ajax() request ruined my PDF file, while requesting it through address bar worked perfectly.
Solution was this:
Include download.js: http://danml.com/download.html
Then use XMLHttpRequest instead of $.ajax() request.
var ajax = new XMLHttpRequest();
ajax.open("GET", '/Admin/GetPdf' + id, true);
ajax.onreadystatechange = function(data) {
if (this.readyState == 4)
{
if (this.status == 200)
{
download(this.response, "report.pdf", "application/pdf");
}
else if (this.responseText != "")
{
alert(this.responseText);
}
}
else if (this.readyState == 2)
{
if (this.status == 200)
{
this.responseType = "blob";
}
else
{
this.responseType = "text";
}
}
};
ajax.send(null);

create a hidden iframe, then in your ajax code above:
url: document.getElementById('myiframeid').src = your_server_side_url,
and remove the window.open(response);

This snippet is for angular js users which will face the same problem, Note that the response file is downloaded using a programmed click event.
In this case , the headers were sent by server containing filename and content/type.
$http({
method: 'POST',
url: 'DownloadAttachment_URL',
data: { 'fileRef': 'filename.pdf' }, //I'm sending filename as a param
headers: { 'Authorization': $localStorage.jwt === undefined ? jwt : $localStorage.jwt },
responseType: 'arraybuffer',
}).success(function (data, status, headers, config) {
headers = headers();
var filename = headers['x-filename'];
var contentType = headers['content-type'];
var linkElement = document.createElement('a');
try {
var blob = new Blob([data], { type: contentType });
var url = window.URL.createObjectURL(blob);
linkElement.setAttribute('href', url);
linkElement.setAttribute("download", filename);
var clickEvent = new MouseEvent("click", {
"view": window,
"bubbles": true,
"cancelable": false
});
linkElement.dispatchEvent(clickEvent);
} catch (ex) {
console.log(ex);
}
}).error(function (data, status, headers, config) {
}).finally(function () {
});

I have found a solution that solved this problem for me (blank pdf when using jquery ajax). I've found this magical solution here: https://www.py4u.net/discuss/904599 (Answer 2) and it involves adding xhrFields to your ajax call:
xhrFields: {
responseType: 'blob'
}
My working example:
$.ajax({
url: "myUrl",
type: 'GET',
headers: {"token": mySecurityToken},
xhrFields: {
responseType: 'blob'
},
data: {id: myId}
}).done(function( data, statusText, xhr ) {
var filename = "";
var disposition = xhr.getResponseHeader("Content-Disposition");
if (disposition && (disposition.indexOf("attachment") !== -1) || disposition.indexOf("filename") !== -1) {
var filenameRegex = /filename[^;=\n]*=(([""]).*?\2|[^;\n]*)/;
var matches = filenameRegex.exec(disposition);
if (matches != null && matches[1])
filename = matches[1].replace(/[""]/g, "");
}
var type = xhr.getResponseHeader("Content-Type");
var blob = new Blob([data], {type: type});
if (typeof window.navigator.msSaveBlob !== "undefined") {
// IE workaround for "HTML7007: One or more blob URLs were revoked by closing the blob for which they were created. These URLs will no longer resolve as the data backing the URL has been freed.
window.navigator.msSaveBlob(blob, filename);
} else {
var URL = window.URL || window.webkitURL;
var downloadUrl = URL.createObjectURL(blob);
if (filename) {
// Use HTML5 a[download] attribute to specify filename.
var a = document.createElement("a");
// Safari doesn"t support this yet.
if (typeof a.download === "undefined") {
window.location = downloadUrl;
} else {
a.href = downloadUrl;
a.download = filename;
document.body.appendChild(a);
a.click();
}
} else {
window.location = downloadUrl;
}
setTimeout(function () {
URL.revokeObjectURL(downloadUrl);
}, 100); // Cleanup
}
})
I hope this will solve this nasty issue for many of you.

var xhr;
var beforeSend = function(){
$('#pleasewaitDL').modal('show');
}
$(function () {
$('#print_brochure_link').click(function(){
beforeSend();
xhr = new XMLHttpRequest();
xhr.open("GET",$('#preparedPrintModalForm').attr('action'), true);
xhr.responseType = "blob";
xhr.onload = function (e) {
if (this.status === 200) {
var file = window.URL.createObjectURL(this.response);
var a = document.createElement("a");
a.href = file;
a.download = this.response.name || "Property Brochure";
console.log(file);
document.body.appendChild(a);
a.click();
window.onfocus = function () {
document.body.removeChild(a)
}
$('#pleasewaitDL').modal('hide');
};
};
xhr.send($('#preparedPrintModalForm').serialize());
});
$('#pleasewaitDLCancel').click(function() {
xhr.abort();
});
});

If you have to work with file-stream (so no physically saved PDF) like we do and you want to download the PDF without page-reload, the following function works for us:
HTML
<div id="download-helper-hidden-container" style="display:none">
<form id="download-helper-form" target="pdf-download-output" method="post">
<input type="hidden" name="downloadHelperTransferData" id="downloadHelperTransferData" />
</form>
<iframe id="pdf-helper-output" name="pdf-download-output"></iframe>
</div>
Javascript
var form = document.getElementById('download-helper-form');
$("#downloadHelperTransferData").val(transferData);
form.action = "ServerSideFunctionWhichWritesPdfBytesToResponse";
form.submit();
Due to the target="pdf-download-output", the response is written into the iframe and therefore no page reload is executed, but the pdf-response-stream is output in the browser as a download.

100% OK for all file types
// download the file
var link = document.createElement('a'),
filename = fname;
link.href = URL.createObjectURL(data);
link.download = filename;
link.click();

Do you have to do it with Ajax? Couldn't it be a possibility to load it in an iframe?

The best usage is to do an anchor or a form with the provided link, but it you need to do a validation or in other cases using jquery the best usage is to add a form and submit it using jquery (don't forget to set your request disposition as attachement on server side).
<form id="pdf-form" action="/link_to/download_your.pdf" accept-charset="UTF-8" method="get">
<input type="hidden" name="data" id="data" value="your data"></form>
and
Download my Pdf
then in jquery
$('#pdf').click(function () {
// your data if it json do it like this JSON.stringify(your_data_as_json)
$('#data').val(data);
$('#pdf-form').submit();
})