I am having a really hard time figuring out how I am going to handle printing in my Nodejs application. I have a website where there is a bunch of purchase numbers. I want the users to print this numbers in a click of a button. These numbers are dynamically generated after querying the database.
I started using this npm library to print the purchase number. When I am developing in my local computer this library is working fine. I made it so that each time the user presses a button in the front end, I make a post request to my Nodejs Server which prints to the printer that I configured locally.
The problem is that I want to eventually deploy my website to Heroku. Website will be used by a group of people sharing the same network and printer. I do not know of a way to set heroku to communicate with the printer using this package.
I also thought that printing directly from the front end might be a better idea, but I have to open google on kiosk mode and then do the same for all the users that are going to use this website. Also, most of the users will be using a tablet device so configuring printer in those devices will be difficult as well.
I did not find anything online that I can use as a reference. Any advice or suggestion will be greatly appreciated.
As for nodeJs printing I have no experience. It seems that you can use certain packages to print a pdf as given in the example answer here: Node.js : How to add print job to printer.
As for generating from html to PDF, that should be easy to find, less easy to style correctly though.
I would recommend doing it from HTML (you could still do the PDF conversion for more stable printing results)
From HTML
As stated, the API is rather limited, you can use window.print to request a print action.
Note though that you have some options to make your life better when calling window.print().
You can create the page in a separate window to get rid of bloat, like navigation etc, or you could actually hide that with css.
You might already be aware of css being included for certain targets e.g. for your website you probably want to use the screen target, but you can create a separate stylesheet for printing.
More info at mozilla
https://developer.mozilla.org/en-US/docs/Web/Guide/Printing
Related
I would like to write a js for an offline website (located on a local Windows server or any other server). It's supposed to look for files like PDFs in several directories and display them as search result on the "website", which isn't a real website, since it's on a local server and not in the web. The PDF is supposed to open in the browser after clicking it. I already have this kind of search engine as a php file, which I wrote with some help from friends. I also want to share this site with other friends. Basically I'll send them the whole folder with the html - document (or the .php site), so they can use it to search for certain pdfs in the folder. Its like a offline wiki for medical research documents. But I don't want them to always install php on their local servers, so they can run my php-searchmachine, thus I need to write it new as a javascript. By google and stack overflow I came across this solution https://www.codegrepper.com/code-examples/javascript/find+file+in+directory+javascript but it seems like that this needs node.js, so all have to install node.js, which is similar to installing php, I guess (im not familiar with node.js). Also I'm not sure if node.js is running on a normal client or server, which is not a webserver.
How can I start with such a project? Is javascript the correct attempt to solve this?
Windows Search has the ability to search PDF contents when boosted by a PDF (index) iFilter, this means the user can search and find instantly a new search word or a saved search it took only a second to hand enter this search (actually took longer to save for double click next time) just for illustration I chose a word I knew was in one file and actually found it is also in two other PDFs.
The problem for your JS coding is how to use JavaScript to interface with Windows Search since using explorer I could not run that search on a remote server shared library drive (I could see their contents as per second screen but for search, had to pull a local library copy down to my documents) and that is where your JS skills come into play. Personally I would avoid JS and use a VLC method to share view via a remote Lan server or simpler invoke a plain text indexed local copy of remote files for download as and when required.
We are currently looking at porting a enterprise silverlight application over to html5. The major roadblock that we have hit is the ability to open files from the user's local disk. Currently they have a document library which just links to files on their computer that they can open from within the app and view or print out. All that I read is that you can only access the local sandbox of the web app with the html5 file api's. We want to load these files from code.
Does anyone know of any workarounds to this?
Thanks
There is no way for html5 to access local file without user selection. But FSO: FileSystemObject works for IE and MAYBE could be regarded as a work around. But still there are some requirements to meet.
It is possible to use chrome's filesystem API to access files on a users local filesytem. So you'd have to be willing to make this a chrome only application.
Using java you can create a "Signed" applet which has access to the local filesystem. (if the applet is signed you can request filesystm permissions)
then there is a tutorial for accessing methods of your java code directly from javascript here: http://docs.oracle.com/javase/tutorial/deployment/applet/invokingAppletMethodsFromJavaScript.html
you should be able to perform something similar from silverlight.
There is no workaround in pure HTML5/Javascript. You need the use of plugins, such as Java or Silverlight (maybe you shouldn't port it after all). As for workarounds, HTML5 gives you an easy way drag and drop multiple files that you could transfer on the server and then display back to your users. Another workaround would be to install a custom agent (a software with only a tray icon) that would send the information about the current user "document library" to server and then again, you could display it back to the user.
Note: I've heard somewhere that browsers will eventually stop supporting plugins. http://www.howtogeek.com/179213/why-browser-plug-ins-are-going-away-and-whats-replacing-them/
Ya, I agree with Markain. However, if you were to limit your audience solely to chrome users, I daresay, you would most likely use some of your users. If Huazhihao is right, then your number of leaving customers should decrease but users who regularly use firefox won't be happy. Overall, I think that this will not work. Otherwise, there would be too many websites that trashed your hard driver (or at least wherever you have the rights to edit/delete files). I think it would be best if your product was setup to synchronize the file whenever an internet connection was detected and a change was made to the file. That way the user would not need to visit the website whenever the file was uploaded. If this is some kind of an error file, then it would be most beneficial if you were to make a link in the application that when clicked, would upload the file to the website and the website were to do whatever was necessary. If this is a purely online thing, then I don't see what business you would have looking through other peoples' files =-). Hope I helped!
Like the title says, I have a requirement to print a part of the browser window to PDF and then send it to the server so that it can be faxed. I have already found a faxing service so the real problem is in figuring out how to generate the pdf to begin with. I have come up with several options to do this, however all of them come with significant downsides. They are:
Use window.print() on a button click along with print media queries and have the user download the resulting PDF and re-upload it to be faxed. The problem with this is that it is a multi-step process and my users would prefer to just click a single button
Use a library like jspdf to generate the pdf, output to a byte array and upload it to the server. This will work, however it looks terrible because I lose all styling and my print media queries will not be applied. So far, this is my best option
Render the HTML server side and generate a PDF from that. This will work fine, however it requires duplicating all of the work I have done client side (this is a SPA app) along with duplicating the maintenance.
Use a rendering service or library to run the client side application in a headless browser and generate the PDF from that output. This would be very complicated from a security perspective as the application lives behind a login page.
I would appreciate any suggestions not listed above as well as any advice on how to eliminate the cons posed by these options. Thanks in advance!
Looks like using jspdf to render the PDF along with a library such as html2canvas to convert the printable region into an image to preserve styles will get the job done. It has taken some work to configure everything properly (and I'm not through yet) but I am confident this solution will be effective.
I have created a webpage but my friends or collegues always copy the source code and copy all the data easily, so is there any way to hide page source option from browser ?
As a rule, if you are putting information on another user's computer (whether because you made a document or they viewed your webpage), you really can't control what they do with it.
This is an issue that larger companies deal with often. Have you heard of DRM? It's a mechanism that companies like to try to use to control how people can connect to their services, use their content and in general, try to exert control over their data while it's on your system.
Now, a web page is a relatively simple container for holding information. You expressed an urge to prevent your friends from copying the source code. You could try to encrypt it, but if it's using local data to decrypt itself, there still isn't going to be anything that stops them from just copying what's in the View Source window and running it again (even if they can't really read it).
I'd suggest that you don't worry about it. If what you have on your page is so important that others shouldn't be able to see it, don't put it on a webpage.
Finally, Google doesn't much care that you're able to view the source to their home page. Why not? Because the value of the search engine isn't in what the home page looks like, but in the data on the back-end that you don't have direct access to. The value is in the algorithms that execute on the server when you hit that Google Search button that queries that data and returns the information you're looking for. There's very little relative value in the generated HTML that you see in the page. Take a leaf from their book and don't stress that they copy your HTML.
No , there isnt any way to do it, however you can disable right clicking in browser via javascript, but still they can use shortkeys to open developer view (in chrome F12) and see the source. You cannot hide html or javascript from client, but maybe you can make it harder to read.
No. Your HTML output is in the user's realm. Even if there was a way to disable view source in one client, a user could use a different one
Always assume that your site's HTML is fully available to end users.
Yes and no. You can definitely make HTML and JS harder to intrepret by obfuscating your code - that is, taking your code and making it look confusing. Here is a tool that can do that: http://www.colddata.com/developers/online_tools/obfuscator.shtml
However, these things all use code, and code can be decrypted through any number of methods. If you post a song to the internet, even if they cannot find the mp3, they can simply record their speakers. If you upload an image and prevent users from downloading it, they can take a screenshot or use their camera. In order for HTML and Javascript to work, it has to be intrepreted by their computer, and even if you do find a way to disable "View Source" there are others ways, like a DOM inspector (F12 in IE/Chrome, Ctrl+Shift+K in Firefox).
As a workaround, use copyright, warn your users they will be punished if they copy your code, and put watermarks, labels and logos over any mp3s or images you don't want stolen. In the end, disabling right clicking (which is also possible, see How do I disable right click on my web page? ) or disabling selection (also possible) does nothing, because there is more than one way to get your code, like searching through temporary internet files.
However, you ask "what if I want a site where my users can log in and I need security? How can I make it so nobody can see my code then? Doesn't it have to be secure and not out in the open?"
And the answer is, yes, it needs to be secure. That's what server-side languages, like PHP, are for. PHP does all the work on the server itself so the user cannot see it. PHP is like a pre-rendered language - rather than doing it in real-time, PHP does all the work beforehand so the user's computer doesn't have to, making the code safe. The code is never put onto the user's computer, because the user's computer doesn't need it. The work is done by the website itself before the page is sent. SSL is often paired with PHP to make absolutely sure that websites have not been hacked.
But HTML and Javascript have to be done in real time on the user's computer, so you cannot disable View Source because it is useless. There are many, many ways that users could get around it, even if View Source is disabled, and even if right clicking is disabled.
If your code doesn't need to be secure, however, I'd recommend you consider keeping it open source. :)
While the subject could sound like I'm looking to do something shifty, I'm not; I maintain an internal web site used by several hundred phone operators, and would like to add the following functionality:
I would like to add a control in the header of all of the web pages that would capture an image of the entire desktop and save the image as a file to a shared network drive to assist in troubleshooting production problems. This screen capture app would be called by JavaScript.
I've researched many threads on this site pertaining to capturing screenshots, and all of the offered applications don't meet my need in one of two ways:
The screen capture application has a GUI that pops up and the user sizes some sort of capture control or interacts with a window to do the capture. The users are not very computer literate, and could not be trusted with using a "pop-up" application correctly-- and it would be impossible to enforce them to save the image file with a common file naming convention. I would like the user to press a single UI control on a web site and have JavaScript make the calls to obtain a screen shot and save the image without any further user interaction.
Some automated applications save the HTML by re-posting to the site and "re-assembles" the individual HTML elements into an image. This will not work as the input data that the operator has typed in needs to be in the image, the site uses AJAX so the visual "state" of the web page will be different from one re-obtained from a POST, and some applications have had (active directory) security issues when trying to interact with our (secured) web sites.
If there isn't an application that will meet this need, I'll just roll my own control in C#. But I'd rather obtain a third-party control. so I don't have to support my own control for life. :-)
Javascript does not provide access to the local system for this functionality due to the security risk.
I believe the only way of doing this on a web page is possibly via an active X control or Java applet (similar to screencast-o-matic) but even then security may be an issue.
I also image unless your own c# control is in a windows forms application it would not work as c# controls that are part of a web site will be run on the server and not the client.
Hope this is of some help.
Well to do that you'll need something to interact with the desktop which can't be done by javascript alone.
You'll need to have an Active X Object to be able to interact with the client's machine. Once you have that, it is easy to just have the object take a picture and save it to the directory.
I believe I have the C# code to take a screen shot. If you want I'll post it.
Some alternatives to ActiveX / Java:
You can create a flash program to do the screen capture. I haven't done this and don't know the details, but I'm fairly sure it can be done.
You can setup a custom protocol for screen capture (eg. screencapture:// ), and in your header include a
Screen Capture
link. You'll need to find a gui-less screen capture program to do the actual capturing and set it up as the handler for that custom protocol.
Did it once. I couldn't find a direct way so did it rendering HTML to canvas, then canvas to image using html2canvas. Canvas to image is a much more common theme so you'll find many tutorials about.
HTML to Canvas
Canvas to image
NOTE: rendering from HTML to canvas may leave some elements behind, like SVG. But overall it did as much as expected.
PSR (problem step recorder) is a great tool for debugging purposes on client machines and it is available on all windows machines by default.
Try below and see if it works for you.
Go to Start->Run and type psr.exe (or just psr) this should open the recorder. This is fairly easy to use, so even users/clients can use it. If it works then try below steps to setup.
Step 1: Register PSR protocol. This tells the browser what to do when a link on the page is referring to PSR protocol (which we will use to open this recorder).
- Create registry values as below
HKEY_CLASSES_ROOT/
PSR/
(Default) "URL:PSR Protocol"
URL Protocol ""
shell/
open/
command/
(Default) psr.exe
If you are not comfortable with creating registry values, download and double click this file.
Use this link for more information.
Step 2: Now create an example html file to test launching PSR.
Save the below code to index.html file and open it.
<html>
<head>
<head>
</head>
<body>
Start Recording
</body>
</head>
</html>
Or download this file and open it.
This should open your PSR. It is easy to use and can record all the information you need for debugging.