I've built a code playground (similar to liveweave) using react. the users can save their "code playgrounds" and access them later. (using firebase db) ,this "code playgrounds"are just made of HTML, CSS, and js. I´m trying to add a functionality which allow the user to download a playground, the idea is that it will generate 3 separate files (one for each language in the playground)
1) is there a way to generate (HTML CSS and js) files and populate them with content client-side?
2) if so, would there be any chance to group those files inside a .rar also client-side?
3) if generating these files client-side is not the optimal solution/not possible, how would you approach this problem?
I was thinking maybe in an express server that queries the data from the db and then response with those files, but I would like to try a client-sided solution
Finally decided to use fileSaver.js package
import { saveAs } from "file-saver";
const saveFiles = () => {
var blob = new Blob([makeHtml(getDocumentCode())], {
type: "text/plain;charset=utf-8",
});
saveAs(blob, `${getFileName()}.html`);
};
first, you need to make a blob out of the content of the file, in this case, it was HTML +css +js code, makeHtml function handles how the HTML document is constructed, then just pass that blob to the saveAs function along the name and extension for the file, then you can use saveFiles in response to any event like onClick
<button onClick={saveFile}>Download<button/>
Related
I am trying to download the pdf from this url :
http://www.africau.edu/images/default/sample.pdf
I followed the example and wrote the code below.
import { saveAs } from "file-saver";
const downloadPDF = ()=>{
var FileSaver = require("file-saver");
FileSaver.saveAs(
"http://www.africau.edu/images/default/sample.pdf",
"somehthing.pdf"
);
}
However, when the downloadPDF function is invoked on the button pressed. The file is not being saved. The pdf is simply being opened in the new tab.
The screenshot of what the pdf looks like in the new tab is shown below.
How do I save the pdf file?
Also, is this approach to get the pdf even valid in the first place or is axios.get() more preferred approach to get the file, then save the response file (response.body) via FileSaver.saveAs()
If the question is unclear, please let me know in the comment before flagging - I will make the necessary update. Thank you
seems like the FileSaver does not help.
However if the file is coming from the server we recommend you to first try to use Content-Disposition attachment response header as it has more cross-browser compatiblity.
as far as I know, there are 2 ways to download file in browser.
server returns a response with header Content-Disposition with value attachment or header Content-Type with value application/octet-stream. Browser will promote the SaveDialog and handle this download for you. This is preferred way to download but this requires you to have control over the server.
you just use ajax or axios to get the data of any file at anywhere. then you create a dummy link to download (like this one). then browser will promote for SaveDialog and then save file to disk. This is just fine for small file but not for large files because you have to store entire file in memory before saving it to local disk.
I think option 2 is appropriate for you.
Example here. In this example, I place a file named abc.json in public folder. Note that the server must enable cors for your website origin. otherwise, there's no way for you to access that file in javascript code.
I've converted an existing web application (HTML5, JS, CSS, etc.) into a Windows UWP app so that (hopefully) I can distribute it via the Windows Store to Surface Hubs so it can run offline. Everything is working fine, except PDF viewing. If I open a PDF in a new window, the Edge-based browser window simply crashes. If I open an IFRAME and load PDFJS into it, that also crashes. What I'd really like to do is just hand off the PDF to the operating system so the user can view it in whatever PDF viewer they have installed.
I've found some windows-specific Javascript APIs that seem promising, but I cannot get them to work. For example:
Windows.System.Launcher.launchUriAsync(
new Windows.Foundation.Uri(
"file:///"+
Windows.ApplicationModel.Package.current.installedLocation.path
.replace(/\//g,"/")+"/app/"+url)).then(function(success) {
if (!success) {
That generates a file:// URL that I can copy into Edge and it shows the PDF, so I know the URL stuff is right. However, in the application it does nothing.
If I pass an https:// URL into that launchUriAsync function, that works. So it appears that function just doesn't like file:// URLs.
I also tried this:
Windows.ApplicationModel.Package.current.installedLocation.getFileAsync(url).then(
function(file) { Windows.System.Launcher.launchFileAsync(file) })
That didn't work either. Again, no error. It just didn't do anything.
Any ideas of other things I could try?
-- Update --
See the accepted answer. Here is the code I ended up using. (Note that all my files are in a subfolder called "app"):
if (location.href.match(/^ms-appx:/)) {
url = url.replace(/\?.+/, "");
Windows.ApplicationModel.Package.current.installedLocation.getFileAsync(("app/" + url).replace(/\//g,"\\")).then(
function (file) {
var fn = performance.now()+url.replace(/^.+\./, ".");
file.copyAsync(Windows.Storage.ApplicationData.current.temporaryFolder,
fn).then(
function (file2) {
Windows.System.Launcher.launchFileAsync(file2)
})
});
return;
}
Turns out you have to turn the / into \ or it won't find the file. And copyAsync refuses to overwrite, so I just use performance.now to ensure I always use a new file name. (In my application, the source file names of the PDFs are auto-generated anyway.) If you wanted to keep the filename, you'd have to add a bunch of code to check whether it's already there, etc.
LaunchFileAsync is the right API to use here. You can't launch a file directly from the install directory because it is protected. You need to copy it first to a location that is accessible for the other app (e.g. your PDF viewer). Use StorageFile.CopyAsync to make a copy in the desired location.
Official SDK sample: https://github.com/Microsoft/Windows-universal-samples/tree/master/Samples/AssociationLaunching
I just thought I'd add a variation on this answer, which combines some details from above with this info about saving a blob as a file in a JavaScript app. My case is that I have a BLOB that represents the data for an epub file, and because of the UWP content security policy, it's not possible simply to force a click on a URL created from the BLOB (that "simple" method is explicitly blocked in UWP, even though it works in Edge). Here is the code that worked for me:
// Copy BLOB to downloads folder and launch from there in Edge
// First create an empty file in the folder
Windows.Storage.DownloadsFolder.createFileAsync(filename,
Windows.Storage.CreationCollisionOption.generateUniqueName).then(
function (file) {
// Open the returned dummy file in order to copy the data to it
file.openAsync(Windows.Storage.FileAccessMode.readWrite).then(function (output) {
// Get the InputStream stream from the blob object
var input = blob.msDetachStream();
// Copy the stream from the blob to the File stream
Windows.Storage.Streams.RandomAccessStream.copyAsync(input, output).then(
function () {
output.flushAsync().done(function () {
input.close();
output.close();
Windows.System.Launcher.launchFileAsync(file);
});
});
});
});
Note that CreationCollisionOption.generateUniqueName handles the file renaming automatically, so I don't need to fiddle with performance.now() as in the answer above.
Just to add that one of the things that's so difficult about UWP app development, especially in JavaScript, is how hard it is to find coherent information. It took me hours and hours to put the above together from snippets and post replies, following false paths and incomplete MS documentation.
You will want to use the PDF APIs https://github.com/Microsoft/Windows-universal-samples/tree/master/Samples/PdfDocument/js
https://github.com/Microsoft/Windows-universal-samples/blob/master/Samples/PdfDocument/js/js/scenario1-render.js
Are you simply just trying to render a PDF file?
Working in Chrome, loading a local html or JS file.
I found many examples of how to load a file that is selected using the Choose File input.
However, didn't figure out how to do it given a file name without using the Choose File input.
The Choose File input returns a File object.
How to create the File object without the Choose File input?
From the File API:
new File(
Array parts,
String filename,
BlobPropertyBag properties
);
But didn't figure out what the parts and properties would be.
Edit: Use case:
I have code coverage results generated as part of a test suite. It is stored as JSON (which is easy to read), but I need to display it with the source code.
So the feature is to load the source code and JSON data, and render them together on a web page using HTML and Javascript.
The file would be opened from the browser and lives on the local machine. There is no server.
The browser cannot load arbitrary files by name from your filesystem without special extensions or other shenanigans. This is a security policy to prevent random web sites from reading files from your hard disk as you browse the internet.
If you're down to do something special like if you want to write a chrome app, you could get access to some nice APIs for accessing the filesystem:
https://developer.chrome.com/apps/fileSystem
The File constructor doesn't read a file from the harddrive, but rater make a virtual file, consider this:
var file = new File(["some", "content"], "/tmp/my-name.txt");
var reader = new FileReader();
reader.onload = function() {
console.log(reader.result); // somecontent
};
No file will be read or stored on the clients machine.
If you are talking about creating files in nodejs then you should take a look at fs.
For security reasons all browsers don't support predefined values on file fields so the answer is you can't.
I need to add a browse button inside my Chrome extension. Users click it and choose a file. I then want to retrieve the file contents (bytes) and do some work on it.
I don't want to have to submit the file to a remote server and then get the response (if that's even doable from inside a Chrome extension), it should be all client-side.
Is this doable inside Chrome extensions?
You should be looking at the FileReader API.
The FileReader object lets web applications asynchronously read the contents of files (or raw data buffers) stored on the user's computer, using File or Blob objects to specify the file or data to read.
A very good basic example of using this interface is in this question.
A minimal example: suppose that you have an <input type="file" id="file"> with a text file selected.
var file = document.getElementById("file").files[0];
var reader = new FileReader();
reader.onload = function(e){
console.log(e.target.result);
}
reader.readAsText(file);
If you need methods other than reading as text (i.e. binary data), see the docs.
Also, this is a good overview: Using files from web applications
Regarding your question it is totally feasible to load and process a file within an extension. I implemented it using message passing https://developer.chrome.com/docs/extensions/mv3/messaging/.
Here is an example of how you can implement it, in my case I used the input file to load an excel. This is my public repo.
https://github.com/juanmachuca95/gomeetplus
We are developing an app that is to download files from HTTP URLs, the extensions/file types of which we will not know until runtime. We've been following this tutorial as a starting point, but since we aren't dealing with images, it hasn't helped us.
The issue is that the code in the tutorial will get you a Blob object and I can't find any code that will allow us to either:
Convert the Blob to a byte array.
Save the Blob straight to the file system.
The ultimate goal is to seamlessly save the file at the given URL to the file system and launch it with the default application, or to just launch it from the URL directly (without the save prompt you get if you just call Windows.System.Launcher.launchUriAsync(uri);).
Any insight anyone might have is greatly appreciated.
Regarding downloading content into byte array:
Using WinJS.xhr with the responseType option as 'arraybuffer' will return the contents in ArrayBuffer. A javascript typed array can be instantiated from the ArrayBuffer for example UInt8Array. This way contents can be read into byte array. code should look something like this:
// todo add other options reqd
var options = { url: url, responseType: 'arraybuffer' };
WinJS.xhr(options).then(function onxhr(ab)
{
var bytes = new Uint8Array(ab, 0, ab.byteLength);
}, function onerror()
{
// handle error
});
Once you take care of permissions to save the file to file system either by user explicitly picking the save file location using SaveFilePicker or pick folder using folder picker - file can be saved on local file system. Also, file can be saved to app data folder.
AFAIK, html/js/css files from local file system or the app data cannot be loaded for security reasons. Although DOM can be manipulated under constraints, to add content. I am not sure of your application requirements. You might need to consider alternatives instead of launching downloaded html files.