Develop Reference

Save file using JavaScript

I have the following code to create a file from Base64.
var byteCharacters =atob(content);
var byteNumbers = new Array(byteCharacters.length);
for (var i = 0; i < byteCharacters.length; i++) {
byteNumbers[i] = byteCharacters.charCodeAt(i);
}
var byteArray = new Uint8Array(byteNumbers);
var blob = new Blob([byteArray]);
var link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
window.navigator.msSaveOrOpenBlob(blob, 'msSaveBlob_testFile.docx');
The problem is that when I execute the msSaveOrOpenBlob it ask the user for downloading/saving of file, what I want is to automatically save it to user c drive.
I think this can be done using ActiveX in IE but even when I used ActiveX to save docx file although it saved the file but it says file is corrupted, but for simple txt file it works fine.
var FileOpener = new ActiveXObject("Scripting.FileSystemObject");
var FilePointer = FileOpener.OpenTextFile("C:\taqi.docx", 2, true);
FilePointer.WriteLine("some text");
FilePointer.Close();
even writing simple string to docx file, give me error of invalid file. But if I open the same docx file in notepad than I can see the text.
Now my question is how can I use the blob object to create file silently. the file can be (txt,docx,ppt,pdf)
Any help will be appreciated.
Thanks

For security purpose browsers don't permit saving files on the user's computer without his permission.
Consider using localstorage to save it in the browser instead :
https://developer.mozilla.org/en-US/docs/Web/API/Window/localStorage

Javascript new File() gem file size

I have the following file structure:
test.html
test.json
And the following JS function:
function get_file(){
var app_path = app.activeDocument.path,
file = new File(app_path + '/test.json');
console.log(file);
}
How can I make the function log the file's content?

I'm not sure if everything you can do in the browsers environment translates to everything you can do in photoshops environment. But you should look at a few things.
Doing This in the Browser
The File object.
https://developer.mozilla.org/en-US/docs/Web/API/File
Notable that it extends the Blob object.
https://developer.mozilla.org/en-US/docs/Web/API/Blob
Which if you researched you would find it can be read using the FileReader.
https://developer.mozilla.org/en-US/docs/Web/API/FileReader
So this would work in the browser but may/may-not work in the photoshop scripting set.
function get_file(){
var app_path = app.activeDocument.path,
file = new File(app_path + '/test.json');
var reader = new FileReader();
reader.onloadend = function() {
console.log(reader.result);
}
reader.readAsText(file);
}
This is asynchronous so you may need to use a callback depending on what you're trying to do with this. You won't be able to return the string from inside the reader.onloadend event.
Doing This in Photoshop
Take a look at their scripting references. Specifically the javascript reference.
All Resources: http://www.adobe.com/devnet/photoshop/scripting.html
Javascript PDF: http://wwwimages.adobe.com/content/dam/Adobe/en/devnet/photoshop/pdfs/photoshop-cc-javascript-ref-2015.pdf
It looks like they don't have the FileReader but instead the File object can be used to read content. The File API begins on page 109 but it's empty! The documentation is a bit pathetic so I can see why you'd have trouble finding this. With some searching I found someone doing this in 2012 (but I don't know if it will still work- worth a shot)
var b = new File("c:\test.txt");
b.open('r');
var str = "";
while(!b.eof) {
str += b.readln();
}
b.close();
alert(str);
Let me know if that works.

Almost no experience in HTML and JavaScript, Having problems with this simple JSON creator [duplicate]

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.

How to get correct MD5 hash after saving canvas as .png in Chrome extension?

I am trying to save image canvas to disk as .png in chrome extension with file name reflecting MD5 hash. For this I use something like this:
var img = document.createElement("img");
img.src=canvas.toDataURL("image/png");
var image_data = atob(img.src.split(',')[1]);
var arraybuffer = new ArrayBuffer(image_data.length);
var view = new Uint8Array(arraybuffer);
for (var i=0; i<image_data.length; i++) {
view[i] = image_data.charCodeAt(i);
}
var blob = new Blob([view], {type: 'image/png'});
var url = (window.webkitURL || window.URL).createObjectURL(blob);
var b = new FileReader;
b.readAsDataURL(blob);
b.onloadend = function () {
filename = SparkMD5.hash(b.result);
}
// ....some code
chrome.downloads.download ({ url, filename+'.png', saveAs: false });
The file is saved correctly, but MD5 hash that I get in code via SparkMD5 is different from the one I see in Windows after the file is saved. I cannot understand why. Experimented a bit with different approaches to saving (directly XMLHttpRequest, etc), but no luck yet. Probably I misunderstand some basic concept, as far as I am a bit of newbee to web programming.
I have also saved files via chrome.pageCapture.saveAsMHTML with the use of FileReader and in that case MD5 are equal.
What is wrong and is there a way to get equal MD5 for filename and final file while saving .png from Chrome extension?

Reading client side text file using Javascript

I want to read a file (on the client side) and get the content in an array. It will be just one file. I have the following and it doesn't work. 'query_list' is a textarea where I want to display the content of the file.
<input type="file" id="file" name="file" enctype="multipart/form-data"/>
<script>
document.getElementById('file').addEventListener('change', readFile, false);
function readFile (evt) {
var files = evt.target.files;
var file = files[0];
var fh = fopen(file, 0);
var str = "";
document.getElementById('query_list').textContent = str;
if(fh!=-1) {
length = flength(fh);
str = fread(fh, length);
fclose(fh);
}
document.getElementById('query_list').textContent = str;
}
</script>
How should I go about it? Eventually I want to loop over the array and run some SQL queries.

If you want to read files on the client using HTML5's FileReader, you must use Firefox, Chrome or IE 10+. If that is true, the following example reads a text file on the client.
your example attempts to use fopen that I have never heard of (on the client)
http://jsfiddle.net/k3j48zmt/
document.getElementById('file').addEventListener('change', readFile, false);
function readFile (evt) {
var files = evt.target.files;
var file = files[0];
var reader = new FileReader();
reader.onload = function(event) {
console.log(event.target.result);
}
reader.readAsText(file)
}
For IE<10 support you need to look into using an ActiveX Object like ADO.Stream Scripting.FileSystemObject http://msdn.microsoft.com/en-us/library/2z9ffy99(v=vs.85).aspx but you'll run into a security problem. If you run IE allowing all ActiveX objects (for your website), it should work.

There is such thing as HTML5 File API to access local files picked by user, without uploading them anywhere.
It is quite new feature, but supported by most of modern browsers.
I strongly recommend to check out this great article to see, how you can use it.
There is one problem with this, you can't read big files (~400 MB and larger) because straight forward FileAPI functions attempting to load entire file into memory.
If you need to read big files, or search something there, or navigate by line index check my LineNavigator, which allows you to read, navigate and search in files of any size. Try it in jsFiddle! It is super easy to use:
var navigator = new FileNavigator(file);
navigator.readSomeLines(0, function linesReadHandler(err, index, lines, eof, progress) {
// Some error
if (err) return;
// Process this line bucket
for (var i = 0; i < lines.length; i++) {
var line = lines[i];
// Do something with it
}
// End of file
if (eof) return;
// Continue reading
navigator.readSomeLines(index + lines.length, linesReadHandler);
});

Well I got beat to the answer but its different:
<input type="file" id="fi" />
<button onclick="handleFile(); return false;">click</button>
function handleFile() {
var preview = document.getElementById('prv')
var file = document.getElementById('fi').files[0];
var div = document.body.appendChild(document.createElement("div"));
div.innerHTML = file.getAsText("utf-8");
}
This will work in FF 3.5 - 3.6, and that's it. FF 4 and WebKit you need to use the FileReader as mentioned by Juan Mendes.
For IE you may find a Flash solution.

I work there, but still wanted to contribute because it works well: You can use the filepicker.io read api to do exactly this. You can pass in an dom element and get the contents back, for text or binary data, even in IE8+