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();
}

Download PDF file with AJAX and HTML button (no jquery)

I want to download a PDF file when I press an HTML button. I want the click event to be in a JS file.
I need something that do the same thig as the code below but in a JS file :
<a href="url" download>
<button>Download</button>
</a>
I tried to follow this but it doesn't create my button:
var req = new XMLHttpRequest();
req.open("GET", "url", true);
req.responseType = "blob";
req.onreadystatechange = function () {
if (req.readyState === 4 && req.status === 200) {
// test for IE
if (typeof window.navigator.msSaveBlob === 'function') {
window.navigator.msSaveBlob(req.response, "PdfName-" + new Date().getTime() + ".pdf");
} else {
var blob = req.response;
var link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
link.download = "PdfName-" + new Date().getTime() + ".pdf";
// append the link to the document body
document.body.appendChild(link);
link.click();
}
}
};
req.send();

If you already have the URL, and you just want the file to be downloaded, use an invisible link, and click it for the user:
function triggerDownload(url, filename) {
const a = document.createElement('a');
a.href = url;
a.download = filename;
a.style.display = `none`;
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
}
Note the adding to the document, which is required for the link to count as a real link.

Just made it work, here is my working code
const blob = new Blob([response], { type: 'application/pdf' });
const link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
link.download = "filename.pdf";
link.click();

I would agree with mike, you don't need any ajax to download it
if you want to add the timestamp for when you downloaded it, just change the download attribute dynamical
Download
or better yet add it in the backend using content-disposition attachment header

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>

How to download file using JavaScript only

I have an only JavaScript page and .asmx page. I want to download file
using only JavaScript how can I download the file. I want to download a particular resume.
I am getting resume here,
var res = data[i].resume;

You may use different third-party libraries:
jQuery.fileDownload
It takes URL as an input and downloads a file while shows a loading dialog.
Github: https://github.com/johnculviner/jquery.fileDownload
Demo: http://jqueryfiledownload.apphb.com/
Usage:
$.fileDownload(requestUrl, {
preparingMessageHtml: "Downloading...",
failMessageHtml: "Error, please try again."
});
FileSaver.js
It takes Blob object as an input and downloads it. Blob can be acquired using XMLHttpRequest.
Github: https://github.com/eligrey/FileSaver.js/
Demo: http://eligrey.com/demos/FileSaver.js/
Usage:
var xhr = new XMLHttpRequest();
xhr.open("GET", requestUrl);
xhr.responseType = "blob";
xhr.onload = function () {
saveAs(this.response, 'filename.txt'); // saveAs is a part of FileSaver.js
};
xhr.send();
It may also be used to save canvas-based images, dynamically generated text and any other Blobs.
Or write it yourself
function saveData(blob, fileName) // does the same as FileSaver.js
{
var a = document.createElement("a");
document.body.appendChild(a);
a.style = "display: none";
var url = window.URL.createObjectURL(blob);
a.href = url;
a.download = fileName;
a.click();
window.URL.revokeObjectURL(url);
}
Now, if it is a text file, you can simply download it, create a blob, and save it:
$.ajax({
url: requestUrl,
processData: false,
dataType: 'text'
}).done(function(data) {
var blob = new Blob([data], { type: "text/plain; encoding=utf8" });
saveData(blob, 'filename.txt');
});
Or you can use XMLHttpRequest which works great for any types of files, including binary:
var xhr = new XMLHttpRequest();
xhr.open("GET", requestUrl);
xhr.responseType = "blob";
xhr.onload = function () {
saveData(this.response, 'filename'); // saveAs is now your function
};
xhr.send();
Here is the working demo. Note that this fiddle downloads a file right after opening it. The file is just a random source file from GitHub.

Actually, There is a javascript library called FileSaver.js, FileSaver.js saving file on the client-side. it can help you achieve this.
here: https://github.com/eligrey/FileSaver.js
Usage:
<script src="http://cdn.jsdelivr.net/g/filesaver.js"></script>
<script>
function SaveAsFile(t,f,m) {
try {
var b = new Blob([t],{type:m});
saveAs(b, f);
} catch (e) {
window.open("data:"+m+"," + encodeURIComponent(t), '_blank','');
}
}
SaveAsFile("text","filename.txt","text/plain;charset=utf-8");
</script>

If you use jQuery you can do some like that:
var getFile = function( path_to_file, callback ) {
$.ajax( {
url: path_to_file,
success: callback
} );
};
getFile( 'path_to_your_asmx_page', function( file_as_text ) {
console.log( file_as_text );
} );
Call getFile and you'll get file content in callback function

Use the code below.
var sampleBytes = base64ToArrayBuffer('THISISTHETESTDATA');
saveByteArray([sampleBytes], 'ashok.text');
function base64ToArrayBuffer(base64)
{
var binaryString = window.atob(base64);
var binaryLen = binaryString.length;
var bytes = new Uint8Array(binaryLen);
for (var i = 0; i < binaryLen; i++)
{
var ascii = binaryString.charCodeAt(i);
bytes[i] = ascii;
}
return bytes;
}
var saveByteArray = (function ()
{
var a = document.createElement("a");
document.body.appendChild(a);
a.style = "display: none";
return function (data, name) {
var blob = new Blob(data, {type: "text/plain"}),
url = window.URL.createObjectURL(blob);
a.href = url;
a.download = name;
a.click();
window.URL.revokeObjectURL(url);
};
}());

document.getElementById('a').click() doesn't works in IE

I have a code which worked in Chrome and Firefox but not work in IE. It downloads a file stored in a mysql db as a blob record by a link.
Could anyone propose a solution that also works in IE?
The code:
function download(filename, data) {
var a = document.createElement("a");
var blob = b64toBlob(data, "application/octet-stream");
url = window.URL.createObjectURL(blob);
a.href = url;
a.download = filename;
a.click();
document.getElementById('a').click();
window.URL.revokeObjectURL(url);
}

In IE 8 and 9, data URIs can only be used for images, but not for navigation or JavaScript generated file downloads:
function download(filename, data) {
var a = document.createElement("a");
var blob = b64toBlob(data, "application/octet-stream");
url = window.URL.createObjectURL(blob);
a.href = url;
a.download = filename;
a.click();
navigator.msSaveBlob(blob, filename);
//document.getElementById('a').onclick();
window.URL.revokeObjectURL(url);
}