I'd like to download a database compressed as a .gz file in a cordova application and extract it to create a local WEBSQL database.
Is this posible?
I have the need to do this because my app needs to work offline, besides that this database I have to sync is so big that is unthinkable to download it uncompressed.
This sync only happens one time in my app. So after that is not a big deal.
Thanks in advance!
PD: I'm currently downloading each table separately but it takes too long, the code is a mess with all the callbacks and stuff. A compressed file with all data would be much more helpful.
You can find gz uncompressors for JavaScript in this question: JavaScript implementation of Gzip
Related
I'm trying to run a D3 visualization that reads data from a local .csv file (same directory as the javascript and HTML files), and I am looking for a way to parse this .csv file into an array of dictionaries than can then be fed to D3. However, all the solutions that I'm seeing in the Internet require either an or downloading the csv online/creating some kind of webserver or request, but I would like to avoid those. Is there any way to just open the file and parse it, sort of like in Python that you can just open('myfile.csv').
I would like to end up with a File object that can be passed to Papaparse. Thank you in advance, and sorry is this duplicated, I've been looking for this for a while so I thought I should try to ask it.
When you are in the browser you run JS in a sandbox that has no access to the local filesystem. This is for security reasons. However, you can popup a file open dialog on the browser and import it in memory. Please check this SO thread and links:
Is it possible to upload a file in memory using javascript for processing before sending it to server?
For reference if thread is deleted:
https://developer.mozilla.org/en-US/docs/web/api/file
https://developer.mozilla.org/en-US/docs/web/api/file/using_files_from_web_applications
Also, https://techoverflow.net/2018/03/30/reading-an-uploaded-file-into-memory-using-pure-javascript/
I'm trying to create a file server to serve a bunch of files for download and have a web-based UI to search/filter and download the files.
Right now i'm using a basic FTP server and i'm planning to create a simple (flask+js) web app that will redirect me to the ftp url for the selected file so it can be downloaded. The web app is needed so I can create my own tagging and filtering system.
However, i'm having trouble finding out how to download whole directories and folders as a zip. Basically like how google drive can have a "Download as zip" function while still keeping the raw folder available for browsing.
Is there a way to do this?
This involves working with "blobs", a JavaScript way of dealing with streamable binary data.
I haven't tried this particular library myself, but there's an article here about using the JSZip library specifically for the kind of thing I think you're talking about: https://davidwalsh.name/javascript-zip
I have a requirement where I want to show the file preview to the users.
There are various file types which are supported like; .pdf, .xlsx, .doc, .rar, .jpeg, .png and many more.
When user clicks on the preview it should open the file in popup where preview of the file is shown to him. User can Zoom-in, Zoom-out, Download the file. Just as you can see into gmail for attachment preview.
Please, can anyone guide me to any relevant library or helpful resource for the same.
Thanks in advance
There are two main ways you can do this.
1) Server-side: Render previews once server-side (on file upload) into jpg/png images, and store the previews on the server. This is the easiest to implement on the client side, but requires extra storage on the server.
2) Client-side: Render the previews 'live' with javascript in browser, this reduces the amount the server has to do/store, but does require the client to fully download the file in-memory before it can render the preview, which for large files could be an issue. Also, you would need javascript libraries included for likely each individual file type, since most libraries will target one specific file format.
Server-Side is probably the recommended way to go. What are you using for your web server?
You are looking at creating document viewer.
Belive me its big work as browser does not understand these formats. Browser can render images directly on canvas but it does not know how to render the other files. So, any file other than image formats, one need to save them temporarily on server and then stream on the browser and show them using the respective file viewer.
You can convert doc and xlsx files to pdf and show these files using pdf viewer (http://ngmodules.org/modules/ng-pdfviewer). There are plenty of document converters available on internet (however you will need to check the licensing terms as most of them are GPL licensed, hense can not be used in commercial projects).
If you want to save this work then go for third party server those take all paint to convert documents in html5 such as https://crocodoc.com/why-crocodoc/
You can also try using google doc viewer google doc veiwer
This question is fairly broad. I'm not going through all the steps of how to implement an attachment viewer directive, but here are some pointers you might find useful.
To allow the user to download the file, you simply put a download link somewhere. If you are hosting the attachment on Amazon S3, Google Cloud Storage or some other cloud storage service, check their documentation. If you're downloading the files from your own server, make sure to set the Content-Disposition HTTP response header to attachment; filename="ORIGINAL_FILENAME", where ORIGINAL_FILENAME is the file name you want to user to see in the save dialog that appears when they click the download link.
Now on to the viewer.
For PDF files, I'd use pdfJS. There's an angular directive for it here.
You could look at something like CloudConvert for other files, to convert ehm to a PDF, and then displaying them in pdfJS, but then you probably want to store the PDF on your server as well, in addition to the original files, which requires extra storage. You might also be able to use the Google Docs viewer, or Office 365 viewer, as described in this answer.
Is it possible to send a images to the Pebble watch using PebbleKit Javascript sendAppMessage.
My idea is to load an image from the web and send it to the watch and display them there. If an image is not possible directly then I was thinking of drawing the image to a canvas and trying to get bitmap data from the canvas to send to the watch.
Is any of this possible now or am I thinking of things that have not been done yet. If possible how? If not done yet how might you do it?
Looking to brainstorm and share possible code ideas.
I should also mention that I do not want to use an iOS or Android app, only the PebbleKit JS.
There is a complete example of an app that uses JavaScript to download images in the pebble-hacks Github repository. This github projects hosts different non-official yet written by team pebble.
The one you are looking for is pebble-faces. The image download part is built in a separate source file to be easily re-used in your own project.
I also added a PHP port for the Python script here
https://github.com/logbon72/pebblebitmap
It might come in handy if your run PHP applications that need to do conversion on the fly.
Say I have a webapp which executes in its entirety on the client-side. Its purpose is to act as a file conversion utility, for example converting a user's local stored word document into a PDF.
So with the user's permission, the app can read a specified local file and process it, in memory, into PDF format.
How can I get the user to 'download' the result? since the data is held in the browser's memory anyway, I do not wish to upload it to some server.
[edit]
No flash based solutions
Expected file sizes to be up to 15mb
The solution for my case will be to use the HTML5 FileSaver API.
Perhaps this question should just be closed as it is effectively a duplicate of
Using HTML5/Javascript to generate and save a file
Thanks to aefxx