Develop Reference

How to download Promise<Blob> with browser instead of Javascript [duplicate]

How do you set the name of a blob file in JavaScript when force downloading it through window.location?
function newFile(data) {
var json = JSON.stringify(data);
var blob = new Blob([json], {type: "octet/stream"});
var url = window.URL.createObjectURL(blob);
window.location.assign(url);
}
Running the above code downloads a file instantly without a page refresh that looks like:
bfefe410-8d9c-4883-86c5-d76c50a24a1d
I want to set the filename as my-download.json instead.

The only way I'm aware of is the trick used by FileSaver.js:
Create a hidden <a> tag.
Set its href attribute to the blob's URL.
Set its download attribute to the filename.
Click on the <a> tag.
Here is a simplified example (jsfiddle):
var saveData = (function () {
var a = document.createElement("a");
document.body.appendChild(a);
a.style = "display: none";
return function (data, fileName) {
var json = JSON.stringify(data),
blob = new Blob([json], {type: "octet/stream"}),
url = window.URL.createObjectURL(blob);
a.href = url;
a.download = fileName;
a.click();
window.URL.revokeObjectURL(url);
};
}());
var data = { x: 42, s: "hello, world", d: new Date() },
fileName = "my-download.json";
saveData(data, fileName);
I wrote this example just to illustrate the idea, in production code use FileSaver.js instead.
Notes
Older browsers don't support the "download" attribute, since it's part of HTML5.
Some file formats are considered insecure by the browser and the download fails. Saving JSON files with txt extension works for me.

I just wanted to expand on the accepted answer with support for Internet Explorer (most modern versions, anyways), and to tidy up the code using jQuery:
$(document).ready(function() {
saveFile("Example.txt", "data:attachment/text", "Hello, world.");
});
function saveFile (name, type, data) {
if (data !== null && navigator.msSaveBlob)
return navigator.msSaveBlob(new Blob([data], { type: type }), name);
var a = $("<a style='display: none;'/>");
var url = window.URL.createObjectURL(new Blob([data], {type: type}));
a.attr("href", url);
a.attr("download", name);
$("body").append(a);
a[0].click();
window.URL.revokeObjectURL(url);
a.remove();
}
Here is an example Fiddle. Godspeed.

Same principle as the solutions above. But I had issues with Firefox 52.0 (32 bit) where large files (>40 MBytes) are truncated at random positions. Re-scheduling the call of revokeObjectUrl() fixes this issue.
function saveFile(blob, filename) {
if (window.navigator.msSaveOrOpenBlob) {
window.navigator.msSaveOrOpenBlob(blob, filename);
} else {
const a = document.createElement('a');
document.body.appendChild(a);
const url = window.URL.createObjectURL(blob);
a.href = url;
a.download = filename;
a.click();
setTimeout(() => {
window.URL.revokeObjectURL(url);
document.body.removeChild(a);
}, 0)
}
}
jsfiddle example

Late, but since I had the same problem I add my solution:
function newFile(data, fileName) {
var json = JSON.stringify(data);
//IE11 support
if (window.navigator && window.navigator.msSaveOrOpenBlob) {
let blob = new Blob([json], {type: "application/json"});
window.navigator.msSaveOrOpenBlob(blob, fileName);
} else {// other browsers
let file = new File([json], fileName, {type: "application/json"});
let exportUrl = URL.createObjectURL(file);
window.location.assign(exportUrl);
URL.revokeObjectURL(exportUrl);
}
}

This is my solution. From my point of view, you can not bypass the <a>.
function export2json() {
const data = {
a: '111',
b: '222',
c: '333'
};
const a = document.createElement("a");
a.href = URL.createObjectURL(
new Blob([JSON.stringify(data, null, 2)], {
type: "application/json"
})
);
a.setAttribute("download", "data.json");
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
}
<button onclick="export2json()">Export data to json file</button>

saveFileOnUserDevice = function(file){ // content: blob, name: string
if(navigator.msSaveBlob){ // For ie and Edge
return navigator.msSaveBlob(file.content, file.name);
}
else{
let link = document.createElement('a');
link.href = window.URL.createObjectURL(file.content);
link.download = file.name;
document.body.appendChild(link);
link.dispatchEvent(new MouseEvent('click', {bubbles: true, cancelable: true, view: window}));
link.remove();
window.URL.revokeObjectURL(link.href);
}
}

Working example of a download button, to save a cat photo from an url as "cat.jpg":
HTML:
<button onclick="downloadUrl('https://i.imgur.com/AD3MbBi.jpg', 'cat.jpg')">Download</button>
JavaScript:
function downloadUrl(url, filename) {
let xhr = new XMLHttpRequest();
xhr.open("GET", url, true);
xhr.responseType = "blob";
xhr.onload = function(e) {
if (this.status == 200) {
const blob = this.response;
const a = document.createElement("a");
document.body.appendChild(a);
const blobUrl = window.URL.createObjectURL(blob);
a.href = blobUrl;
a.download = filename;
a.click();
setTimeout(() => {
window.URL.revokeObjectURL(blobUrl);
document.body.removeChild(a);
}, 0);
}
};
xhr.send();
}

window.location.assign did not work for me. it downloads fine but downloads without an extension for a CSV file on Windows platform. The following worked for me.
var blob = new Blob([csvString], { type: 'text/csv' });
//window.location.assign(window.URL.createObjectURL(blob));
var link = window.document.createElement('a');
link.href = window.URL.createObjectURL(blob);
// Construct filename dynamically and set to link.download
link.download = link.href.split('/').pop() + '.' + extension;
document.body.appendChild(link);
link.click();
document.body.removeChild(link);

this is a good easy solution for it.
function downloadBloob(blob,FileName) {
var link = document.createElement("a"); // Or maybe get it from the current document
link.href = blob;
link.download = FileName;
link.click();
}

Save virtual file get by REST API on Internet Explorer download parameter doesn't work

I have this code that correctly works on most of browsers except IE:
<a href="http://xxx.xxx.xxx.xxx/presets/current" download="configuration.bin">
Save
</a>
the problem is that download parameter doesn't work on IE.
To correct it I've tried this code
var request = new XMLHttpRequest();
request.open('GET', "http://xxx.xxx.xxx.xxx/presets/current", true);
request.responseType = 'blob';
request.onload = function() {
var reader = new FileReader();
reader.readAsDataURL(request.response);
reader.onload = function(e){
var blob = new Blob( [e.target.result] );
navigator.msSaveBlob( blob, 'configuration.bin' );
};
};
request.send();
On AngularJS I've also tried using $http like this code:
$http({method: 'GET', url: "http://xxx.xxx.xxx.xxx/presets/current"})
.success(function(data, status, headers, config) {
var blob = new Blob([data]);
navigator.msSaveBlob( blob, 'configuration.bin' );
})
The problem is that the file size downloaded on Chrome is 134K and the file downloaded on IE with this code is 180K
Question: How could I save file exactly as I get it?

In IE, you can only use msSaveBlob to download files and you need to set the blob type correctly according to your demand. The cross-browser method should be like this:
//change to the type you need
var blob = new Blob([byteArray], { type: 'application/pdf' });
//output file name
var fileName = "test.pdf";
//detect whether the browser is IE/Edge or another browser
if (window.navigator && window.navigator.msSaveOrOpenBlob) {
//To IE or Edge browser, using msSaveorOpenBlob method to download file.
window.navigator.msSaveBlob(blob, fileName);
} else {
//To another browser, create a tag to downlad file.
const url = window.URL.createObjectURL(blob);
const a = document.createElement('a');
document.body.appendChild(a);
a.setAttribute('style', 'display: none');
a.href = url;
a.download = fileName;
a.click();
window.URL.revokeObjectURL(url);
a.remove();
}
I use this method to download file and the size is the same in IE and Chrome. You could also refer to these similar threads: link1, link2.

How to download file with post method? [duplicate]

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();
}
});

image does not download with it's own extension

I have used below code to download image with given name. But this seems does not download image with it's own image extension.
Here is HTML
<a id="btnDownload" href="www.mywebsite.com/images/myimage.jpg" onClick="downloadImage(www.mywebsite.com/images/myimage.jpg);" >download</a>
and code
function downloadImage(sUrl){
window.URL = window.URL || window.webkitURL;
var xhr = new XMLHttpRequest();
xhr.open('GET', sUrl, true);
xhr.responseType = 'blob';
xhr.onload = function(e) {
var res = xhr.response;
var blob = new Blob([res], {type:'image'});
url = window.URL.createObjectURL(blob);
var a = document.createElement("a");
a.href = url;
a.download = "My image name";
document.body.appendChild(a);
a.click();
};
xhr.send();
}
What i want is i want downloaded image with "My image name"."extension". Here image does have alternative extension like jpeg, png, gif.
But this code always download file without extension. Any changes here?

To get the extension in your example you could do:
a.download = "My image Name." + window.URL.split('.').pop();
Yet I would work with different data-attributes:
<html>
<!--
You can put the href and the name you want to see in different data attributes.
Also one can add IE support.
-->
<head>
<script>
//e:=<a [data-name] [data-href]>
function downloadMe(e){
var tF = e.getAttribute('data-name');
var tURL = e.getAttribute('data-href')
var tR = new XMLHttpRequest();
tR.open('GET', tURL, true);
tR.responseType = 'blob';
tR.onload = function(e){
var tB = this.response;
if(window.top.navigator.msSaveOrOpenBlob){
//Store Blob in IE
window.top.navigator.msSaveOrOpenBlob(tB, tF)
}
else{
//Store Blob in others
var tA = document.body.appendChild(document.createElement('a'));
tA.href = URL.createObjectURL(tB);
tA.download = tF;
tA.style.display = 'none';
tA.click();
tA.parentNode.removeChild(tA)
}
};
tR.send();
return false
}
</script>
</head>
<body>
<a href = '#' data-href = 'A.png' data-name = 'My Name.png' onclick = 'return downloadMe(this)'>download</a>
</body>
</html>

ajax -> save as dialog before downloading

I am programming an embedded Device in C with a webserver. One Task is to download files from this devices. I want to Download serveral files at once, so i created an ajax-request, which using POST-Request and a bunch of filenames to return a zip-file (i create these zip-file on my own on the device). Everything works fine, but the dialog save as appears after the whole zip-file was transmitted.
At server-side the device is sending the 200 OK-, Content-Type: application/octet-stream- and Content-Disposition: attachment; filename="testzip.zip"-headers.
At client-side i using this javascript-code(got this from stackoverlfow: Handle file download from ajax post):
function downloadFiles(filenames) {
var xhr = new XMLHttpRequest();
xhr.open('POST', /file-save/, true);
xhr.responseType = 'arraybuffer';
xhr.onload = function () {
if (this.status === 200) {
var filename = "test.zip";
var type = xhr.getResponseHeader('Content-Type');
var blob = new Blob([this.response], { type: type });
var URL = window.URL || window.webkitURL;
var downloadUrl = URL.createObjectURL(blob);
// use HTML5 a[download] attribute to specify filename
var a = document.createElement("a");
a.href = downloadUrl;
a.download = filename;
document.body.appendChild(a);
a.click();
setTimeout(function () { URL.revokeObjectURL(downloadUrl); }, 100); // cleanup
}
};
xhr.send(filenames);
}
The if-statement if (this.status === 200) is reached, when the whole file is transmitted. If the size of the file is small, there is not a problem, because the user isn't recognizing the lack of time. But is the file about 50MB the user can't see any download although the file is downloading. In my opinion the reason is a.click(), because the click-method imitades the begin of the download.
Is there sombody who can help me out with a solution or some hints?
By the way, jquery isn't an option!.
Thanks for any help
EDIT: my goal is to download a file like on every webpage with large files, where i get a dialog with the location to save and i can see the download-progress.
SOLUTION(Hint from Herr Derb):
function downloadFiles(filenames) {
var xhr = new XMLHttpRequest();
xhr.open('POST', /file_save/, true);
xhr.onload = function () {
if (this.status === 200) {
var mydisp = xhr.getResponseHeader('Content-Disposition');
var save_response = xhr.responseText;
var var_json_format = JSON.parse(save_response);
/* check for errors */
if(var_json_format["error"]) {
return;
} else {
status = _.findWhere(var_json_format["link"], {id : 'status'}).value;
download_id = _.findWhere(var_json_format["link"], {id : 'download_id'}).value;
}
if(status != "active") {
return;
}
var filename = "test.zip";
var downloadUrl = "/file_save/" + download_id;
var a = document.createElement("a");
a.href = downloadUrl;
a.download = filename;
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
setTimeout(function () { URL.revokeObjectURL(downloadUrl); }, 100); // cleanup
}
};
xhr.send(filenames);
return;
}

Your first request should only create the zip file on your server and return a link to reach it. After you received that link on the client site, simply execute it. This way, everything will happen as you desire, as it will be a regular file download.
And ss soon the download is finished, your free to delete the file again.