I've been fiddling with WebGL lately, and have gotten a Collada reader working. Problem is it's pretty slow (Collada is a very verbose format), so I'm going to start converting files to a easier to use format (probably JSON). I already have the code to parse the file in JavaScript, so I may as well use it as my exporter too! The problem is saving.
Now, I know that I can parse the file, send the result to the server, and have the browser request the file back from the server as a download. But in reality the server has nothing to do with this particular process, so why get it involved? I already have the contents of the desired file in memory. Is there any way that I could present the user with a download using pure JavaScript? (I doubt it, but might as well ask...)
And to be clear: I am not trying to access the filesystem without the users knowledge! The user will provide a file (probably via drag and drop), the script will transform the file in memory, and the user will be prompted to download the result. All of which should be "safe" activities as far as the browser is concerned.
[EDIT]: I didn't mention it upfront, so the posters who answered "Flash" are valid enough, but part of what I'm doing is an attempt to highlight what can be done with pure HTML5... so Flash is right out in my case. (Though it's a perfectly valid answer for anyone doing a "real" web app.) That being the case it looks like I'm out of luck unless I want to involve the server. Thanks anyway!
Simple solution for HTML5 ready browsers...
function download(filename, text) {
var pom = document.createElement('a');
pom.setAttribute('href', 'data:text/plain;charset=utf-8,' + encodeURIComponent(text));
pom.setAttribute('download', filename);
if (document.createEvent) {
var event = document.createEvent('MouseEvents');
event.initEvent('click', true, true);
pom.dispatchEvent(event);
}
else {
pom.click();
}
}
Usage
download('test.txt', 'Hello world!');
OK, creating a data:URI definitely does the trick for me, thanks to Matthew and Dennkster pointing that option out! Here is basically how I do it:
1) get all the content into a string called "content" (e.g. by creating it there initially or by reading innerHTML of the tag of an already built page).
2) Build the data URI:
uriContent = "data:application/octet-stream," + encodeURIComponent(content);
There will be length limitations depending on browser type etc., but e.g. Firefox 3.6.12 works until at least 256k. Encoding in Base64 instead using encodeURIComponent might make things more efficient, but for me that was ok.
3) open a new window and "redirect" it to this URI prompts for a download location of my JavaScript generated page:
newWindow = window.open(uriContent, 'neuesDokument');
That's it.
HTML5 defined a window.saveAs(blob, filename) method. It isn't supported by any browser right now. But there is a compatibility library called FileSaver.js that adds this function to most modern browsers (including Internet Explorer 10+). Internet Explorer 10 supports a navigator.msSaveBlob(blob, filename) method (MSDN), which is used in FileSaver.js for Internet Explorer support.
I wrote a blog posting with more details about this problem.
Saving large files
Long data URIs can give performance problems in browsers. Another option to save client-side generated files, is to put their contents in a Blob (or File) object and create a download link using URL.createObjectURL(blob). This returns an URL that can be used to retrieve the contents of the blob. The blob is stored inside the browser until either URL.revokeObjectURL() is called on the URL or the document that created it is closed. Most web browsers have support for object URLs, Opera Mini is the only one that does not support them.
Forcing a download
If the data is text or an image, the browser can open the file, instead of saving it to disk. To cause the file to be downloaded upon clicking the link, you can use the the download attribute. However, not all web browsers have support for the download attribute. Another option is to use application/octet-stream as the file's mime-type, but this causes the file to be presented as a binary blob which is especially user-unfriendly if you don't or can't specify a filename. See also 'Force to open "Save As..." popup open at text link click for pdf in HTML'.
Specifying a filename
If the blob is created with the File constructor, you can also set a filename, but only a few web browsers (including Chrome & Firefox) have support for the File constructor. The filename can also be specified as the argument to the download attribute, but this is subject to a ton of security considerations. Internet Explorer 10 and 11 provides its own method, msSaveBlob, to specify a filename.
Example code
var file;
var data = [];
data.push("This is a test\n");
data.push("Of creating a file\n");
data.push("In a browser\n");
var properties = {type: 'text/plain'}; // Specify the file's mime-type.
try {
// Specify the filename using the File constructor, but ...
file = new File(data, "file.txt", properties);
} catch (e) {
// ... fall back to the Blob constructor if that isn't supported.
file = new Blob(data, properties);
}
var url = URL.createObjectURL(file);
document.getElementById('link').href = url;
<a id="link" target="_blank" download="file.txt">Download</a>
function download(content, filename, contentType)
{
if(!contentType) contentType = 'application/octet-stream';
var a = document.createElement('a');
var blob = new Blob([content], {'type':contentType});
a.href = window.URL.createObjectURL(blob);
a.download = filename;
a.click();
}
Take a look at Doug Neiner's Downloadify which is a Flash based JavaScript interface to do this.
Downloadify is a tiny JavaScript + Flash library that enables the generation and saving of files on the fly, in the browser, without server interaction.
Simple Solution!
<a download="My-FileName.txt" href="data:application/octet-stream,HELLO-WORLDDDDDDDD">Click here</a>
Works in all Modern browsers.
I've used FileSaver (https://github.com/eligrey/FileSaver.js) and it works just fine.
For example, I did this function to export logs displayed on a page.
You have to pass an array for the instanciation of the Blob, so I just maybe didn't write this the right way, but it works for me.
Just in case, be careful with the replace: this is the syntax to make this global, otherwise it will only replace the first one he meets.
exportLogs : function(){
var array = new Array();
var str = $('#logs').html();
array[0] = str.replace(/<br>/g, '\n\t');
var blob = new Blob(array, {type: "text/plain;charset=utf-8"});
saveAs(blob, "example.log");
}
You can generate a data URI. However, there are browser-specific limitations.
I found two simple approaches that work for me. First, using an already clicked a element and injecting the download data. And second, generating an a element with the download data, executing a.click() and removing it again. But the second approach works only if invoked by a user click action as well. (Some) Browser block click() from other contexts like on loading or triggered after a timeout (setTimeout).
<!DOCTYPE HTML>
<html>
<head>
<meta charset="UTF-8">
<script type="text/javascript">
function linkDownload(a, filename, content) {
contentType = 'data:application/octet-stream,';
uriContent = contentType + encodeURIComponent(content);
a.setAttribute('href', uriContent);
a.setAttribute('download', filename);
}
function download(filename, content) {
var a = document.createElement('a');
linkDownload(a, filename, content);
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
}
</script>
</head>
<body>
download
<button onclick="download('test.txt', 'Hello World!');">download</button>
</body>
</html>
try
let a = document.createElement('a');
a.href = "data:application/octet-stream,"+encodeURIComponent('"My DATA"');
a.download = 'myFile.json';
a.click(); // we not add 'a' to DOM so no need to remove
If you want to download binary data look here
Update
2020.06.14 I upgrade Chrome to 83.0 and above SO snippet stop works (due to sandbox security restrictions) - but JSFiddle version works - here
Here is a link to the data URI method Mathew suggested, it worked on safari, but not well because I couldn't set the filetype, it gets saved as "unknown" and then i have to go there again later and change it in order to view the file...
http://www.nihilogic.dk/labs/canvas2image/
You can use localStorage. This is the Html5 equivalent of cookies. It appears to work on Chrome and Firefox BUT on Firefox, I needed to upload it to a server. That is, testing directly on my home computer didn't work.
I'm working up HTML5 examples. Go to http://faculty.purchase.edu/jeanine.meyer/html5/html5explain.html
and scroll to the maze one. The information to re-build the maze is stored using localStorage.
I came to this article looking for HTML5 JavaScript for loading and working with xml files. Is it the same as older html and JavaScript????
As previously mentioned the File API, along with the FileWriter and FileSystem APIs can be used to store files on a client's machine from the context of a browser tab/window.
However, there are several things pertaining to latter two APIs which you should be aware of:
Implementations of the APIs currently exist only in Chromium-based browsers (Chrome & Opera)
Both of the APIs were taken off of the W3C standards track on April 24, 2014, and as of now are proprietary
Removal of the (now proprietary) APIs from implementing browsers in the future is a possibility
A sandbox (a location on disk outside of which files can produce no effect) is used to store the files created with the APIs
A virtual file system (a directory structure which does not necessarily exist on disk in the same form that it does when accessed from within the browser) is used represent the files created with the APIs
Here are simple examples of how the APIs are used, directly and indirectly, in tandem to do this:
BakedGoods*
bakedGoods.get({
data: ["testFile"],
storageTypes: ["fileSystem"],
options: {fileSystem:{storageType: Window.PERSISTENT}},
complete: function(resultDataObj, byStorageTypeErrorObj){}
});
Using the raw File, FileWriter, and FileSystem APIs
function onQuotaRequestSuccess(grantedQuota)
{
function saveFile(directoryEntry)
{
function createFileWriter(fileEntry)
{
function write(fileWriter)
{
var dataBlob = new Blob(["Hello world!"], {type: "text/plain"});
fileWriter.write(dataBlob);
}
fileEntry.createWriter(write);
}
directoryEntry.getFile(
"testFile",
{create: true, exclusive: true},
createFileWriter
);
}
requestFileSystem(Window.PERSISTENT, grantedQuota, saveFile);
}
var desiredQuota = 1024 * 1024 * 1024;
var quotaManagementObj = navigator.webkitPersistentStorage;
quotaManagementObj.requestQuota(desiredQuota, onQuotaRequestSuccess);
Though the FileSystem and FileWriter APIs are no longer on the standards track, their use can be justified in some cases, in my opinion, because:
Renewed interest from the un-implementing browser vendors may place them right back on it
Market penetration of implementing (Chromium-based) browsers is high
Google (the main contributer to Chromium) has not given and end-of-life date to the APIs
Whether "some cases" encompasses your own, however, is for you to decide.
*BakedGoods is maintained by none other than this guy right here :)
This thread was invaluable to figure out how to generate a binary file and prompt to download the named file, all in client code without a server.
First step for me was generating the binary blob from data that I was saving. There's plenty of samples for doing this for a single binary type, in my case I have a binary format with multiple types which you can pass as an array to create the blob.
saveAnimation: function() {
var device = this.Device;
var maxRow = ChromaAnimation.getMaxRow(device);
var maxColumn = ChromaAnimation.getMaxColumn(device);
var frames = this.Frames;
var frameCount = frames.length;
var writeArrays = [];
var writeArray = new Uint32Array(1);
var version = 1;
writeArray[0] = version;
writeArrays.push(writeArray.buffer);
//console.log('version:', version);
var writeArray = new Uint8Array(1);
var deviceType = this.DeviceType;
writeArray[0] = deviceType;
writeArrays.push(writeArray.buffer);
//console.log('deviceType:', deviceType);
var writeArray = new Uint8Array(1);
writeArray[0] = device;
writeArrays.push(writeArray.buffer);
//console.log('device:', device);
var writeArray = new Uint32Array(1);
writeArray[0] = frameCount;
writeArrays.push(writeArray.buffer);
//console.log('frameCount:', frameCount);
for (var index = 0; index < frameCount; ++index) {
var frame = frames[index];
var writeArray = new Float32Array(1);
var duration = frame.Duration;
if (duration < 0.033) {
duration = 0.033;
}
writeArray[0] = duration;
writeArrays.push(writeArray.buffer);
//console.log('Frame', index, 'duration', duration);
var writeArray = new Uint32Array(maxRow * maxColumn);
for (var i = 0; i < maxRow; ++i) {
for (var j = 0; j < maxColumn; ++j) {
var color = frame.Colors[i][j];
writeArray[i * maxColumn + j] = color;
}
}
writeArrays.push(writeArray.buffer);
}
var blob = new Blob(writeArrays, {type: 'application/octet-stream'});
return blob;
}
The next step is to get the browser to prompt the user to download this blob with a predefined name.
All I needed was a named link I added in the HTML5 that I could reuse to rename the initial filename. I kept it hidden since the link doesn't need display.
<a id="lnkDownload" style="display: none" download="client.chroma" href="" target="_blank"></a>
The last step is to prompt the user to download the file.
var data = animation.saveAnimation();
var uriContent = URL.createObjectURL(data);
var lnkDownload = document.getElementById('lnkDownload');
lnkDownload.download = 'theDefaultFileName.extension';
lnkDownload.href = uriContent;
lnkDownload.click();
When testing the "ahref" method, I found that the web developer tools of Firefox and Chrome gets confused. I needed to restart the debugging after the a.click() was issued. Same happened with the FileSaver (it uses the same ahref method to actually make the saving). To work around it, I created new temporary window, added the element a into that and clicked it there.
function download_json(dt) {
var csv = ' var data = ';
csv += JSON.stringify(dt, null, 3);
var uricontent = 'data:application/octet-stream,' + encodeURI(csv);
var newwin = window.open( "", "_blank" );
var elem = newwin.document.createElement('a');
elem.download = "database.js";
elem.href = uricontent;
elem.click();
setTimeout(function(){ newwin.close(); }, 3000);
}
You can use this to save text and other data:
function downloadFile(name, data) {
let a = document.createElement("a");
if (typeof a.download !== "undefined") a.download = name;
a.href = URL.createObjectURL(new Blob([data], {
type: "application/octet-stream"
}));
a.dispatchEvent(new MouseEvent("click"));
}
This function will create an Anchor element, set the name via .download (if supported), assign a url (.href) created from an object (URL.createObjectURL), in this case a Blob object, and dispatch a click event. In short: it's as if you're clicking a download link.
Example code
downloadFile("textfile.txt", "A simple text file");
downloadFile(
"circle.svg",
`<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
<circle cx="50" cy="50" r="42" />
</svg>`
);
downloadFile(
"utf8string.txt",
new Uint8Array([85, 84, 70, 45, 56, 32, 115, 116, 114, 105, 110, 103]) // "UTF-8 string"
);
This function also accepts File, Blob and MediaSource:
function downloadFile(name, data) {
if (!(data instanceof File || data instanceof Blob || data instanceof MediaSource)) {
return downloadFile(name, new Blob([data], {
type: "application/octet-stream"
}));
}
let a = document.createElement("a");
if (typeof a.download !== "undefined") a.download = name;
a.href = URL.createObjectURL(data);
a.dispatchEvent(new MouseEvent("click"));
}
Or you could use two functions:
function downloadFile(name, data) {
return downloadObject(new Blob([data], {
type: "application/octet-stream"
}));
}
function downloadObject(name, object) {
let a = document.createElement("a");
if (typeof a.download !== "undefined") a.download = name;
a.href = URL.createObjectURL(object);
a.dispatchEvent(new MouseEvent("click"));
}
Here is a tutorial to export files as ZIP:
Before getting started, there is a library to save files, the name of library is fileSaver.js, You can find this library here. Let's get started, Now, include the required libraries:
<script src="https://cdnjs.cloudflare.com/ajax/libs/jszip/3.1.4/jszip.min.js" type="text/javascript"></script>
<script type="text/javascript" src="https://fastcdn.org/FileSaver.js/1.1.20151003/FileSaver.js" ></script>
Now copy this code and this code will download a zip file with a file hello.txt having content Hello World. If everything thing works fine, this will download a file.
<script type="text/javascript">
var zip = new JSZip();
zip.file("Hello.txt", "Hello World\n");
zip.generateAsync({type:"blob"})
.then(function(content) {
// see FileSaver.js
saveAs(content, "file.zip");
});
</script>
This will download a file called file.zip. You can read more here: http://www.wapgee.com/story/248/guide-to-create-zip-files-using-javascript-by-using-jszip-library
For simple files like 'txt' or'js' you can use the package fs-browsers.
It has nice and easy download and export methods for client-side which do not invole any server.
import { exportFile } from 'fs-browsers';
const onExportClick = (textToExport) => {
// Export to txt file
exportFile(textToExport);
}
If you want to change the name of the file, or even it's type you can do it easily with this:
import { exportFile } from 'fs-browsers';
const onExportClick = (textToExport) => {
// Export to js file called 'file.js'
exportFile(textToExport, { fileName: 'file.js' });
}
For more complex files you will need to involve a server as you said.
The package can also does that with excel files ('xls') if that is what you need.
import { exportFile, EXCEL_FILE } from 'fs-browsers';
const data = [{ "id": 5, "name": "John", "grade": 90, "age": 15 }, { "id": 7, "name": "Nick", "grade": 70, "age": 17 }];
const headings = ["Student ID", "Student Name", "Test Grade", "Student Age"];
exportFile(data, { type: EXCEL_FILE, headings: headings, fileName: 'grades.xls' });
Maybe in the future there eill be other kind of files too.
Related
I've written a NodeJS/Express application that generates and downloads an excel document (created using ExcelJS) upon the user pressing a button. When the user presses the button, the file is generated then downloaded to the user's default download location. I'd prefer the user be able to select where they'd like to download the file upon pressing the button. Is this possible?
My current JavaScript code is as follows:
export_button.onclick = async function() {
await fetch('/download', {
method: 'POST'
})
.then(resp => resp.blob())
.then(blob => {
const url = window.URL.createObjectURL(blob);
const a = document.createElement('a');
a.style.display = 'none';
a.href = url;
a.download = 'document.xlsx';
document.body.appendChild(a);
a.click();
window.URL.revokeObjectURL(url);
});
}
This is possible in desktop versions of latest Chrome-based browsers (Chrome, Edge, Opera).
Current support:
https://caniuse.com/mdn-api_window_showsavefilepicker
https://wicg.github.io/file-system-access/#api-showsavefilepicker
https://wicg.github.io/file-system-access/#enumdef-wellknowndirectory
We use this for working with PDF files: https://webpdf.pro/doc/ (draft for next release).
Note that you can suggest a file name and folder, customize the file type list, offer multiple types!
In fact, we have a method called exactly that: <pdf-file>.saveAs().
Online version of Visual Studio Code is another recent user: https://vscode.dev/.
Apple and Firefox are likely to drag their feet on this one citing privacy/security concerns for at least the next few months though.
async function saveFile(){
var mystring = "Hello World!";
var myblob = new Blob([mystring], {
type: 'text/plain'
});
if( window.showSaveFilePicker ) {
const opts = {
types: [{
description: 'MYfile',
accept: {'text/plain': ['.txt']},
}],
suggestedName: 'myFileText',
};
var handle = await showSaveFilePicker(opts);
var writable = await handle.createWritable();
await writable.write( myblob );
writable.close();
}else{
alert( "xxx" );
}
}
<button id="botonx" onClick="saveFile()" >Save File</button>
I don't believe this is possible, no. This behaviour is controlled by settings in the user's browser. For most browsers, or perhaps even all of them, the default behaviour is to always download files to a default location without showing a prompt where the user can change its destination or filename. Understandably, you can't change a user's browser settings from JavaScript.
Glad to see I was wrong about this, I didn't realise the File System Access API Cetin Sert's answer describes exists.
It is about exporting extension data from options page.
I have array of objects, with stored page screenshots encoded in base64, and some other minor obj properties. I'm trying to export them with this code:
exp.onclick = expData;
function expData() {
chrome.storage.local.get('extData', function (result) {
var dataToSave = result.extData;
var strSt = JSON.stringify(dataToSave);
downloadFn('extData.txt', strSt);
});
}
function downloadFn(filename, text) {
var fLink = document.createElement('a');
fLink .setAttribute('href', 'data:text/plain;charset=utf-8,' + encodeURIComponent(text));
fLink .setAttribute('download', filename);
fLink .click();
}
On button click, get data from storage, stringify it, create fake link, set attributes and click it.
Code works fine if resulting file is under ~1.7 MB, but everything above that produce option page to crash and extension gets disabled.
I can console.log(strSt) after JSON.stringify and everything works fine no matter of the size, if I don't pass it to download function..
Is there anything I can do to fix the code and avoid crash?...or is there any limitation is size when using this methods?
I solved this, as Xan suggested, switching to chrome.downloads (it's extra permission, but works fine)
What I did is just replacing code in downloadFN function, it's cleaner that way
function downloadFn(filename, text) {
var eucTxt = encodeURIComponent(text);
chrome.downloads.download({'url': 'data:text/plain;charset=utf-8,'+eucTxt, 'saveAs': false, 'filename': filename});
}
note that using URL.createObjectURL(new Blob([ text ])) also produce same crashing of extension
EDIT:
as #dandavis pointed (and RobW confirmed), converting to Blob also works
(I had messed code that was producing crash)
This is a better way of saving data locally, because on browser internal downloads page, dataURL downloads can clutter page and if file is too big (long URL), it crashes browser. They are presented as actual URLs (which is raw saved data) while blob downloads are only with id
function downloadFn(filename, text) {
var vLink = document.createElement('a'),
vBlob = new Blob([text], {type: "octet/stream"}),
vUrl = window.URL.createObjectURL(vBlob);
vLink.setAttribute('href', vUrl);
vLink.setAttribute('download', filename);
vLink.click();
}
I have been looking for a way to initiate a file download of data that only exists within the code executing on the user's browser (as opposed to initiating a download from the server), and indicate the file name in the process.
A search of StackOverflow turns up a number of promising posts that don't quite do what I need.
This answer is not IE-compatible and doesn't allow specifying a file name anyway.
This question provides a few ways to initiate downloads, but the answers that allow specifying a file name are not IE compatible and require user interaction, while other answers don't allow specifying a file name.
Is there a way to initiate a file download from JavaScript that:
Downloads client-side data
Does not require the user to manually initiate the download
Allows specifying the filename of the downloaded file
After much searching around and trying approaches from various places, I was able to come up with the following.
The tryAnchorDownload() approach should work on modern versions of FireFox and Chrome, and is a cleaned-up version of code provided in this forum post.
The trySaveAsDownload() approach should theoretically work on any major modern browser, though Safari may not respect the specified file name. It requires the FileSaver.js library and some browsers may need the Blob.js polyfill.
You can call the main function here like this:
initiateFileDownload(bytes, "myFile.txt");
where bytes is a Uint8Array of the file's bytes.
function byteArrayToBase64(bytes) {
var chArray = Array.prototype.map.call(bytes,
function (byte) { return String.fromCharCode(byte); });
return window.btoa(chArray.join(""));
}
var octetStreamMimeType = "application/octet-stream";
function tryAnchorDownload(fileBytes, fileName) {
var aElement = document.createElement("a"),
event;
if ("download" in aElement) {
aElement.setAttribute("download", fileName);
aElement.href = "data:" + octetStreamMimeType +
";base64," + byteArrayToBase64(fileBytes);
document.body.appendChild(aElement);
event = document.createEvent("MouseEvents");
event.initMouseEvent("click", true, false, window, 0, 0, 0, 0, 0,
false, false, false, false, 0, null);
aElement.dispatchEvent(event);
document.body.removeChild(aElement);
return true;
}
return false;
}
function trySaveAsDownload(fileBytes, fileName) {
var blob;
if (window.saveAs) {
blob = new Blob([fileBytes], { type: octetStreamMimeType });
saveAs(blob, fileName);
return true;
}
return false;
}
// fileBytes is a Uint8Array
function initiateFileDownload(fileBytes, fileName) {
return tryAnchorDownload(fileBytes, fileName) ||
trySaveAsDownload(fileBytes, fileName);
}
A more thorough (and probably more efficient) alternative to the byteArrayToBase64() function above can be found on MDN.
If for example you follow the link:
data:application/octet-stream;base64,SGVsbG8=
The browser will prompt you to download a file consisting of the data held as base64 in the hyperlink itself. Is there any way of suggesting a default name in the markup? If not, is there a JavaScript solution?
Use the download attribute:
<a download='FileName' href='your_url'>
The download attribute works on Chrome, Firefox, Edge, Opera, desktop Safari 10+, iOS Safari 13+, and not IE11.
Chrome makes this very simple these days:
function saveContent(fileContents, fileName)
{
var link = document.createElement('a');
link.download = fileName;
link.href = 'data:,' + fileContents;
link.click();
}
HTML only: use the download attribute:
<a download="logo.gif" href="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7">Download transparent png</a>
Javascript only: you can save any data URI with this code:
function saveAs(uri, filename) {
var link = document.createElement('a');
if (typeof link.download === 'string') {
link.href = uri;
link.download = filename;
//Firefox requires the link to be in the body
document.body.appendChild(link);
//simulate click
link.click();
//remove the link when done
document.body.removeChild(link);
} else {
window.open(uri);
}
}
var file = 'data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7'
saveAs(file, 'logo.gif');
Chrome, Firefox, and Edge 13+ will use the specified filename.
IE11, Edge 12, and Safari 9 (which don't support the download attribute) will download the file with their default name or they will simply display it in a new tab, if it's of a supported file type: images, videos, audio files, …
According to RFC 2397, no, there isn't.
Nor does there appear to be any attribute of the <a> element that you can use either.
However HTML5 has subsequently introduced the download attribute on the <a> element, although at the time of writing support is not universal (no MSIE support, for example)
I've looked a bit in firefox sources in netwerk/protocol/data/nsDataHandler.cpp
data handler only parses content/type and charset, and looks if there is ";base64"
in the string
the rfc specifices no filename and at least firefox handles no filename for it,
the code generates a random name plus ".part"
I've also checked firefox log
[b2e140]: DOCSHELL 6e5ae00 InternalLoad data:application/octet-stream;base64,SGVsbG8=
[b2e140]: Found extension '' (filename is '', handling attachment: 0)
[b2e140]: HelperAppService::DoContent: mime 'application/octet-stream', extension ''
[b2e140]: Getting mimeinfo from type 'application/octet-stream' ext ''
[b2e140]: Extension lookup on '' found: 0x0
[b2e140]: Ext. lookup for '' found 0x0
[b2e140]: OS gave back 0x43609a0 - found: 0
[b2e140]: Searched extras (by type), rv 0x80004005
[b2e140]: MIME Info Summary: Type 'application/octet-stream', Primary Ext ''
[b2e140]: Type/Ext lookup found 0x43609a0
interesting files if you want to look at mozilla sources:
data uri handler: netwerk/protocol/data/nsDataHandler.cpp
where mozilla decides the filename: uriloader/exthandler/nsExternalHelperAppService.cpp
InternalLoad string in the log: docshell/base/nsDocShell.cpp
I think you can stop searching a solution for now, because I suspect there is none :)
as noticed in this thread html5 has download attribute, it works also on firefox 20 http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#attr-hyperlink-download
The following Javascript snippet works in Chrome by using the new 'download' attribute of links and simulating a click.
function downloadWithName(uri, name) {
var link = document.createElement("a");
link.download = name;
link.href = uri;
link.click();
}
And the following example shows it's use:
downloadWithName("data:,Hello%2C%20World!", "helloWorld.txt")
No.
The entire purpose is that it's a datastream, not a file. The data source should not have any knowledge of the user agent handling it as a file... and it doesn't.
you can add a download attribute to the anchor element.
sample:
<a download="abcd.cer"
href="data:application/stream;base64,MIIDhTC......">down</a>
Using service workers, this is finally possible in the truest sense.
Create a fake URL. For example /saveAs/myPrettyName.jpg
Use URL in <a href, <img src, window.open( url ), absolutely anything that can be done with a "real" URL.
Inside the worker, catch the fetch event, and respond with the correct data.
The browser will now suggest myPrettyName.jpg even if the user opens the file in a new tab, and tries to save it there. It will be exactly as if the file had come from the server.
// In the service worker
self.addEventListener( 'fetch', function(e)
{
if( e.request.url.startsWith( '/blobUri/' ) )
{
// Logic to select correct dataUri, and return it as a Response
e.respondWith( dataURLAsRequest );
}
});
Look at this link:
http://lists.w3.org/Archives/Public/uri/2010Feb/0069.html
Quote:
It even works (as in, doesn't cause a problem) with ;base64 at the end
like this (in Opera at least):
data:text/plain;charset=utf-8;headers=Content-Disposition%3A%20attachment%3B%20filename%3D%22with%20spaces.txt%22%0D%0AContent-Language%3A%20en;base64,4oiaDQo%3D
Also there is some info in the rest messages of the discussion.
There is a tiny workaround script on Google Code that worked for me:
http://code.google.com/p/download-data-uri/
It adds a form with the data in it, submits it and then removes the form again. Hacky, but it did the job for me. Requires jQuery.
This thread showed up in Google before the Google Code page and I thought it might be helpful to have the link in here, too.
Here is a jQuery version based off of Holf's version and works with Chrome and Firefox whereas his version seems to only work with Chrome. It's a little strange to add something to the body to do this but if someone has a better option I'm all for it.
var exportFileName = "export-" + filename;
$('<a></a>', {
"download": exportFileName,
"href": "data:," + JSON.stringify(exportData, null,5),
"id": "exportDataID"
}).appendTo("body")[0].click().remove();
This one works with Firefox 43.0 (older not tested):
dl.js:
function download() {
var msg="Hello world!";
var blob = new File([msg], "hello.bin", {"type": "application/octet-stream"});
var a = document.createElement("a");
a.href = URL.createObjectURL(blob);
window.location.href=a;
}
dl.html
<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8"/>
<title>Test</title>
<script type="text/javascript" src="dl.js"></script>
</head>
<body>
<button id="create" type="button" onclick="download();">Download</button>
</body>
</html>
If button is clicked it offered a file named hello.bin for download. Trick is to use File instead of Blob.
reference: https://developer.mozilla.org/de/docs/Web/API/File
(This answer has been made deprecated by newer technology, but will be kept here for historical interest.)
It's kind of hackish, but I've been in the same situation before. I was dynamically generating a text file in javascript and wanted to provide it for download by encoding it with the data-URI.
This is possible with minormajor user intervention. Generate a link right-click me and select "Save Link As..." and save as "example.txt". As I said, this is inelegant, but it works if you do not need a professional solution.
This could be made less painful by using flash to copy the name into the clipboard first. Of course if you let yourself use Flash or Java (now with less and less browser support I think?), you could probably find a another way to do this.
<a href=.. download=.. > works for left-click and right-click -> save link as..,
but <img src=.. download=.. > doesn't work for right-click -> save image as.. , "Download.jped" is suggested.
If you combine both:<a href=.. download=..><img src=..></a>
it works for left-click, right-click -> save link as.., right-click -> save image as..
You have to write the data-uri twice (href and src), so for large image files it is better to copy the uri with javascript.
tested with Chrome/Edge 88
var isIE = /*#cc_on!#*/false || !!document.documentMode; // At least IE6
var sessionId ='\n';
var token = '\n';
var caseId = CaseIDNumber + '\n';
var url = casewebUrl+'\n';
var uri = sessionId + token + caseId + url;//data in file
var fileName = "file.i4cvf";// any file name with any extension
if (isIE)
{
var fileData = ['\ufeff' + uri];
var blobObject = new Blob(fileData);
window.navigator.msSaveOrOpenBlob(blobObject, fileName);
}
else //chrome
{
window.requestFileSystem = window.requestFileSystem || window.webkitRequestFileSystem;
window.requestFileSystem(window.TEMPORARY, 1024 * 1024, function (fs) {
fs.root.getFile(fileName, { create: true }, function (fileEntry) {
fileEntry.createWriter(function (fileWriter) {
var fileData = ['\ufeff' + uri];
var blob = new Blob(fileData);
fileWriter.addEventListener("writeend", function () {
var fileUrl = fileEntry.toURL();
var link = document.createElement('a');
link.href = fileUrl;
link.download = fileName;
document.body.appendChild(link);
link.click();
document.body.removeChild(link);
}, false);
fileWriter.write(blob);
}, function () { });
}, function () { });
}, function () { });
}
You actually can achieve this, in Chrome and FireFox.
Try the following url, it will download the code that was used.
data:text/html;base64,PGEgaHJlZj0iZGF0YTp0ZXh0L2h0bWw7YmFzZTY0LFBHRWdhSEpsWmowaVVGVlVYMFJCVkVGZlZWSkpYMGhGVWtVaUlHUnZkMjVzYjJGa1BTSjBaWE4wTG1oMGJXd2lQZ284YzJOeWFYQjBQZ3BrYjJOMWJXVnVkQzV4ZFdWeWVWTmxiR1ZqZEc5eUtDZGhKeWt1WTJ4cFkyc29LVHNLUEM5elkzSnBjSFErIiBkb3dubG9hZD0idGVzdC5odG1sIj4KPHNjcmlwdD4KZG9jdW1lbnQucXVlcnlTZWxlY3RvcignYScpLmNsaWNrKCk7Cjwvc2NyaXB0Pg==
If for example you follow the link:
data:application/octet-stream;base64,SGVsbG8=
The browser will prompt you to download a file consisting of the data held as base64 in the hyperlink itself. Is there any way of suggesting a default name in the markup? If not, is there a JavaScript solution?
Use the download attribute:
<a download='FileName' href='your_url'>
The download attribute works on Chrome, Firefox, Edge, Opera, desktop Safari 10+, iOS Safari 13+, and not IE11.
Chrome makes this very simple these days:
function saveContent(fileContents, fileName)
{
var link = document.createElement('a');
link.download = fileName;
link.href = 'data:,' + fileContents;
link.click();
}
HTML only: use the download attribute:
<a download="logo.gif" href="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7">Download transparent png</a>
Javascript only: you can save any data URI with this code:
function saveAs(uri, filename) {
var link = document.createElement('a');
if (typeof link.download === 'string') {
link.href = uri;
link.download = filename;
//Firefox requires the link to be in the body
document.body.appendChild(link);
//simulate click
link.click();
//remove the link when done
document.body.removeChild(link);
} else {
window.open(uri);
}
}
var file = 'data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7'
saveAs(file, 'logo.gif');
Chrome, Firefox, and Edge 13+ will use the specified filename.
IE11, Edge 12, and Safari 9 (which don't support the download attribute) will download the file with their default name or they will simply display it in a new tab, if it's of a supported file type: images, videos, audio files, …
According to RFC 2397, no, there isn't.
Nor does there appear to be any attribute of the <a> element that you can use either.
However HTML5 has subsequently introduced the download attribute on the <a> element, although at the time of writing support is not universal (no MSIE support, for example)
I've looked a bit in firefox sources in netwerk/protocol/data/nsDataHandler.cpp
data handler only parses content/type and charset, and looks if there is ";base64"
in the string
the rfc specifices no filename and at least firefox handles no filename for it,
the code generates a random name plus ".part"
I've also checked firefox log
[b2e140]: DOCSHELL 6e5ae00 InternalLoad data:application/octet-stream;base64,SGVsbG8=
[b2e140]: Found extension '' (filename is '', handling attachment: 0)
[b2e140]: HelperAppService::DoContent: mime 'application/octet-stream', extension ''
[b2e140]: Getting mimeinfo from type 'application/octet-stream' ext ''
[b2e140]: Extension lookup on '' found: 0x0
[b2e140]: Ext. lookup for '' found 0x0
[b2e140]: OS gave back 0x43609a0 - found: 0
[b2e140]: Searched extras (by type), rv 0x80004005
[b2e140]: MIME Info Summary: Type 'application/octet-stream', Primary Ext ''
[b2e140]: Type/Ext lookup found 0x43609a0
interesting files if you want to look at mozilla sources:
data uri handler: netwerk/protocol/data/nsDataHandler.cpp
where mozilla decides the filename: uriloader/exthandler/nsExternalHelperAppService.cpp
InternalLoad string in the log: docshell/base/nsDocShell.cpp
I think you can stop searching a solution for now, because I suspect there is none :)
as noticed in this thread html5 has download attribute, it works also on firefox 20 http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#attr-hyperlink-download
The following Javascript snippet works in Chrome by using the new 'download' attribute of links and simulating a click.
function downloadWithName(uri, name) {
var link = document.createElement("a");
link.download = name;
link.href = uri;
link.click();
}
And the following example shows it's use:
downloadWithName("data:,Hello%2C%20World!", "helloWorld.txt")
No.
The entire purpose is that it's a datastream, not a file. The data source should not have any knowledge of the user agent handling it as a file... and it doesn't.
you can add a download attribute to the anchor element.
sample:
<a download="abcd.cer"
href="data:application/stream;base64,MIIDhTC......">down</a>
Using service workers, this is finally possible in the truest sense.
Create a fake URL. For example /saveAs/myPrettyName.jpg
Use URL in <a href, <img src, window.open( url ), absolutely anything that can be done with a "real" URL.
Inside the worker, catch the fetch event, and respond with the correct data.
The browser will now suggest myPrettyName.jpg even if the user opens the file in a new tab, and tries to save it there. It will be exactly as if the file had come from the server.
// In the service worker
self.addEventListener( 'fetch', function(e)
{
if( e.request.url.startsWith( '/blobUri/' ) )
{
// Logic to select correct dataUri, and return it as a Response
e.respondWith( dataURLAsRequest );
}
});
Look at this link:
http://lists.w3.org/Archives/Public/uri/2010Feb/0069.html
Quote:
It even works (as in, doesn't cause a problem) with ;base64 at the end
like this (in Opera at least):
data:text/plain;charset=utf-8;headers=Content-Disposition%3A%20attachment%3B%20filename%3D%22with%20spaces.txt%22%0D%0AContent-Language%3A%20en;base64,4oiaDQo%3D
Also there is some info in the rest messages of the discussion.
There is a tiny workaround script on Google Code that worked for me:
http://code.google.com/p/download-data-uri/
It adds a form with the data in it, submits it and then removes the form again. Hacky, but it did the job for me. Requires jQuery.
This thread showed up in Google before the Google Code page and I thought it might be helpful to have the link in here, too.
Here is a jQuery version based off of Holf's version and works with Chrome and Firefox whereas his version seems to only work with Chrome. It's a little strange to add something to the body to do this but if someone has a better option I'm all for it.
var exportFileName = "export-" + filename;
$('<a></a>', {
"download": exportFileName,
"href": "data:," + JSON.stringify(exportData, null,5),
"id": "exportDataID"
}).appendTo("body")[0].click().remove();
This one works with Firefox 43.0 (older not tested):
dl.js:
function download() {
var msg="Hello world!";
var blob = new File([msg], "hello.bin", {"type": "application/octet-stream"});
var a = document.createElement("a");
a.href = URL.createObjectURL(blob);
window.location.href=a;
}
dl.html
<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8"/>
<title>Test</title>
<script type="text/javascript" src="dl.js"></script>
</head>
<body>
<button id="create" type="button" onclick="download();">Download</button>
</body>
</html>
If button is clicked it offered a file named hello.bin for download. Trick is to use File instead of Blob.
reference: https://developer.mozilla.org/de/docs/Web/API/File
(This answer has been made deprecated by newer technology, but will be kept here for historical interest.)
It's kind of hackish, but I've been in the same situation before. I was dynamically generating a text file in javascript and wanted to provide it for download by encoding it with the data-URI.
This is possible with minormajor user intervention. Generate a link right-click me and select "Save Link As..." and save as "example.txt". As I said, this is inelegant, but it works if you do not need a professional solution.
This could be made less painful by using flash to copy the name into the clipboard first. Of course if you let yourself use Flash or Java (now with less and less browser support I think?), you could probably find a another way to do this.
<a href=.. download=.. > works for left-click and right-click -> save link as..,
but <img src=.. download=.. > doesn't work for right-click -> save image as.. , "Download.jped" is suggested.
If you combine both:<a href=.. download=..><img src=..></a>
it works for left-click, right-click -> save link as.., right-click -> save image as..
You have to write the data-uri twice (href and src), so for large image files it is better to copy the uri with javascript.
tested with Chrome/Edge 88
var isIE = /*#cc_on!#*/false || !!document.documentMode; // At least IE6
var sessionId ='\n';
var token = '\n';
var caseId = CaseIDNumber + '\n';
var url = casewebUrl+'\n';
var uri = sessionId + token + caseId + url;//data in file
var fileName = "file.i4cvf";// any file name with any extension
if (isIE)
{
var fileData = ['\ufeff' + uri];
var blobObject = new Blob(fileData);
window.navigator.msSaveOrOpenBlob(blobObject, fileName);
}
else //chrome
{
window.requestFileSystem = window.requestFileSystem || window.webkitRequestFileSystem;
window.requestFileSystem(window.TEMPORARY, 1024 * 1024, function (fs) {
fs.root.getFile(fileName, { create: true }, function (fileEntry) {
fileEntry.createWriter(function (fileWriter) {
var fileData = ['\ufeff' + uri];
var blob = new Blob(fileData);
fileWriter.addEventListener("writeend", function () {
var fileUrl = fileEntry.toURL();
var link = document.createElement('a');
link.href = fileUrl;
link.download = fileName;
document.body.appendChild(link);
link.click();
document.body.removeChild(link);
}, false);
fileWriter.write(blob);
}, function () { });
}, function () { });
}, function () { });
}
You actually can achieve this, in Chrome and FireFox.
Try the following url, it will download the code that was used.
data:text/html;base64,PGEgaHJlZj0iZGF0YTp0ZXh0L2h0bWw7YmFzZTY0LFBHRWdhSEpsWmowaVVGVlVYMFJCVkVGZlZWSkpYMGhGVWtVaUlHUnZkMjVzYjJGa1BTSjBaWE4wTG1oMGJXd2lQZ284YzJOeWFYQjBQZ3BrYjJOMWJXVnVkQzV4ZFdWeWVWTmxiR1ZqZEc5eUtDZGhKeWt1WTJ4cFkyc29LVHNLUEM5elkzSnBjSFErIiBkb3dubG9hZD0idGVzdC5odG1sIj4KPHNjcmlwdD4KZG9jdW1lbnQucXVlcnlTZWxlY3RvcignYScpLmNsaWNrKCk7Cjwvc2NyaXB0Pg==