I am new to web dev and currently building a very basic page using Html/CSS and JS where users can upload the image and I can download it in my local system. But by default images are getting downloaded in the 'download' section of my desktop and I want to save them to any specific folder. How can I add this functionality?
You can't.
You do not have access to other peoples file managers as that would be a major security risk.
Uhh... You can't manipulate the download folder from frontend. It may be a security risk.
This cannot be done by Javascript (otherwise we could all produce websites which saved files all over a user's local PC).
As the end user in this case you can go into your browser and tell it which folder to save downloads in by default. (And remember to change it back if you want any other downloads to go elsewhere).
Here for example is what I find on Edge on Windows10 when going into Settings>Downloads:
I want to open a file in its Windows default application.
Actually, the scenario is as below:
A file is saved in Database and it is shown as a preview in CKEditor
When I double click on that file, it should open in its default application. The file can be a Word or Excel or PDF file
Then the user will edit the file in that default application
And when the user saves that file or closes the document, it should be updated on the server also it should refresh the file preview in CKEditor
I just want to know if there is any way to open the file in its default application.
Things I have tried:
I tried to use the ActiveX object to open the file, but it is not supported in Chrome and Firefox. And anyway, many forums are saying that it is the end of ActiveX era.
Tried to find if there is any CKEditor plugin, but did not find any.
Thank you in advance for your answer.
Short answer: no. Can you imagine the security nightmare if JavaScript was allowed to execute arbitrary binary files on a user's machine?
Your solution is going to be to find a JavaScript library that allows for handling those files, similar to how PDF.js was made for PDFs in-browser.
I'm wondering if it's possible to for certain JS files to be added to the web extension directory later?
Like say I have an app where users can select certain settings from within the app and those files (js and html files, images or blobs) are somehow added into the extension from the web. Like some sort of ondemand updater without using any native apps but it seems that upgrades are done by the appstores automatically.
I'm reading the files using ajax and adding them to indexeddb but because it could be more than one file that's getting messy.
Say a user wants a certain feature on the extension and there's an html page, js files and images then this gets downloaded to a certain folder inside the installed extension.
function download() { //only saves to downloads directory
var imgurl = "https://www.google.com.hk/images/srpr/logo11w.png";
console.log('download');
browser.downloads.download({url:imgurl},function(downloadId){
console.log("download begin, the downId is:" + downloadId);
});
}
I also tried the chrome download function above but that only works for the downloads folder not the extension folder.
Is there any way to make a custom updater?! I know we can't save to disk but any leniency or workarounds for the extension folder?! Even something silly like making a shell call to some dos (and linux/mac) thing that saves the file to the extension folder. I can fetch the files, just not save them.
Ok so I'll put it as an answer. This is the solution I'm leaning on which works for my scenario and I've listed some alternatives below:
Having the other files as separate extensions and giving the user an install link instead where they can install that extension, then those child extensions talk to the mother extension and they know the address to the resources in their child extension folder, so the mother gets the just the file locations from the children to load those assets from that folder. The child extensions are like bundles of those html and js with a background script which sends the addresses of these items to the mother.
https://developer.chrome.com/extensions/messaging#external
The drawback is that I'll have to see how that affects the urls like if I inject the html page from the child extension folder into the main interface using ajax then I can't use relative url's to any images in that 'cos the urls are relative to the mother extension folder.. I'll have to rewrite the child extension urls with the absolute paths into the html page to load images and js from the child extension html code which has relative urls.
Pros:
Cleaner and more persistent than indexeddb.
Files can be loaded normally from disk.
Cons:
User has to install separate extensions.
URL structure might be a bit confusing, need to rewrite urls if loading html from child. However this is only for image src's and where the javascript is loaded from so it's not such a big deal.
Other Possible Solutions:
Indexeddb which I'm already doing seems to be the preferred way of doing this but I really do not want to store every html asset in indexeddb. The upside is that while extensions need to be installed, this method can be done silently fetching and adding files without user interaction and indexeddb seems to be somewhat persistent. Might still end up using this because it is silent but having to load each asset from a database sounds like a nightmare.
The File Handle Api might have worked if I was working on Firefox only https://wiki.mozilla.org/WebAPI/FileHandleAPI
I haven't tried the shell copy, maybe if I fetch with ajax and then save to disk using some dos function and then doing different save functions for different OS systems.
Filesystem Api only saves to downloads and doesn't work for extensions anyways, so that's useless.
UPDATE
In windows there isn't any sudo, but this worked without admin priveleges for a subfolder (not on the C:\ root though). It would work for a linux only app very nicely. If I just wanted to save a file to a windows machine this might work.
Shell copy method would be to grab the contents of file with ajax from the local or remote location, output to DOS as a stream to save to file on windows. And do this for every operating system with a shell exec command or detect the OS and do that command. This way I can even put the files in the exact folder location.
Like say I make this sort of command from the contents:
//To append you can use >> instead of >
//folder seems necessary, can't save to root without admin
echo the content I want to save > C:\folder\textfile.txt
I thought of calling it using shell exec that only works in nodejs, so digging through the other answers on
How to execute shell command in Javascript
//full code to save file using javascript on windows
var shell = WScript.CreateObject("WScript.Shell");
shell.Run("echo content to save > C:\folder\textfile.txt");
The shell command doesn't seem to work. i can't find what this is for. There doesn't seem to be a shell command in regular javascript for windows. It seems to require IE ActiveX. Doesn't work with Firefox or Chrome.
Extensions can't modify their sources because the browser verifies them and resets/disables the extension if they change. Also, in Firefox the extensions aren't even unpacked.
The solution is actually quite trivial: save the code in any storage (localStorage, chrome.storage.local, IndexedDB) as a string and then add it in your extension page as a standard DOM script element. You'll have to relax the standard CSP a bit for that.
Please, I need some help from you guys. I am developing a Phonegap application for Android that downloads some PDF files on a file explorer style interface and them open the files on the Adobe Reader application. The app works well on success scenarios, but if for some reason the connection drops during the download and you close and reopen the application, when you click the pdf file's icon, he tries to open the file - I cache the files on the internal storage, I only download if the file doesn't exists - and adobe reader shows a error of corrupted file. Is there a way on Cordova that I can check if a file is corrupted, so I can download it again if it is corrupted?
thank you
Wouldn't it be easier to keep a flag for each of the files you download to indicate that the download has completed? Once the file finished downloading you set a flag for that file. That way if a transfer is interrupted then the flag won't be set and you can treat that case as if the file doesn't exist so that your application doesn't try to open an incomplete file.
If you call javascript window.open and pass a url to a .xls file it open on some machines in the browser window. How can you force it into Excel?
Only the users machine can "force" it into Excel. That said, 99% of the time if you send the correct mime-type and a user has Excel, then it will open in Excel assuming they approve.
And only the server can send the correct mime-type. The document type you pass to a JavaScript window.open call will have no effect on this. In fact, calling window.open will at best just open a superfluous window.
It's best to just link to the document with <a href="foo.xls">. And provided your server is sending a mime-type of application/x-excel or application/x-msexcel this will almost always nudge the browser into opening a new window with the Excel document.
If it's just a static file, and you're using Apache on Linux, check for a file called /etc/mime.types, and ensure that it has the following line in there to associate the .xls file extension with the correct MIME type:
application/vnd.ms-excel xls
I'm guessing the location of that file might vary across systems, but it's in /etc/mime.types on my server which is running RHEL4.
AFAIK you can't do this with JavaScript alone. If you have some sort of scripting language on the server's side you can alter the header to force a download.
Here's a simple tutorial in PHP, but you can easily find one in your favorite language.
You cannot force it into Excel. You can allow the browser to handle it whichever way it is configured to do so, or you can try to force it to download the file and let the user open if from their desktop. To force a download, search for "force download" and your server-side language (PHP, ASP.NET, JSP, etc.)
I don't think you can: you cannot call external programs using Javascript for security reasons. Assuming that the user has Excel installed, you may want to open the new window without the address bar to give the user "the illusion" that the file has been opened with Excel in Internet Explorer.
I wouldn't think this is possible from javascript due to security issues, there would be nothing stopping a rogue webpage from opening dozens of excel/word instances.
Could you not set a hyperlink to the url of the .xls, that way the user would get the usual download prompt to view the file.
Set the http content type to the Excel datatype: application/vnd.ms-excel
You shouldn't need to redirect to a new window, but you will get a popup asking the user to save or open the file.
In relation to (2): I'd worry if a browser could launch an external application and load data into it automatically without user intervention.
This is a setting in each user's browser and not in something that can be set by code. So unfortunately you do not have control of that.
You can not, as it depends on the client machine.
For example on Windows if you want it to always open it with Excel, not in the browser window, you have to open My Computer, Tools, Folder Options, File Types, select the XLS type, and click on Advanced. There are two checkboxes: Browse in same window and Open web documents in place. Uncheck both, close browser window, open it again and try again.
However as I said: it depends on the client, you can not force it.
You can do this using LaunchinIE, an ActiveX Control that will enable HTML pages to start whatever application on the client's machine, without security warnings.
Quote from the site: "At last, web pages can start Word, Excel, or any other corporate application without complaints. Securely."
For this you do have to install the control on the user machine and also add the URL that is allowed to execute local applications to the Windows registry.
Another quote from the site: "To ensure security, LaunchinIE needs to be carefully configured client-side; due to this restriction it's only fit for intranet use."
I use LaunchinIE in our training facility so I can use Internet Explorer as a menu which lets the user choose the machine setup. LaunchinIE then calls a batch script that configures the machine to best support the selected training.
Here are the steps to get this pop-up back when opening a saved Excel file.
Right-Click on the windows [START] button and select Explore to open Windows Explorer window will open.
From the menu select Tools \ Folder Options…
• Choose the File Types tab and scroll down the list of files.
• Left-Click to highlight the XLS Microsoft Excel Worksheet file extension and click on the Advanced button.
In the Edit File Type window, Uncheck the “Browse in same window” option.
Click OK button to accept your changes.
Start a new browser session. The next time you open your Excel spreadsheet in your Inbox, you should be prompted with the following window. Be sure to leave the “Always ask before opening this type of file” as checked. Clicking the Open button should now open your file in Excel.