Save javascript output to a file? - javascript

I have php made website. It runs on windows machine. I have a javascript that i have tested that gets me the adobe version used by clients. The problem is that by running the code I'm able to retrieve the Adobe Reader version but cannot saved the output to a file on my server end.
Here is the Javascript code. I took this code from sister stackexchange website.
http://jsfiddle.net/EGbY5/3/
What is the best way to save this information from js? Should i use js or any other scripting? I read this from google that you cannot use js to save files on server? If this is true is there any other way.

I would suggest using AJAX (or a form, if you want the user to explicitly know this is happening) to send a request to your server side code detailing the information you have collected with the script.
The advantage of AJAX is that you can do all of this without the user being explicitly aware of it. The disadvantage is that you rely on their browser supporting Javascript, but since you are already collecting information using Javascript this problem is mute.

Ajax'll do it.
JavaScript source:
var adobeVersion = CheckAdobeVersion();
$.post("script.php", {version: adobeVersion}, function(){});
PHP source:
<?php
$version = $_POST['version'];
write all text to a file("my file.txt") // Pseudo code...
?>

Related

Javascript: Save uploaded file

I would like to save uploaded file using javascript, in my linux server. The code I wrote is:
if (uploadInput.files.length == 0) {
console.log("No file is uploaded. ");
} else {
console.log("File uploaded.");
var file = uploadInput.files[0];
}
Now I would like to save that file as "files/upload.csv". Can anyone please advise, how can I do it?
Thanks in advance
What I'm going to do is walk you through the logic, instead of providing code. There is just not enough information here on what you want to do to provide actual code and the sample you provided is a very small part of what the actual solution would need to include.
I'm assuming the code you wrote above is meant to run on a website visitor's browser (client-side). Client-side code can't save to a server. What it can do, is send the file contents to the server. But then you'd need something on the server side to process that file contents and actually save it to the server-side files directory.
One method to send the file contents from the client to the server is to use AJAX - you can do this with native javascript, but I would recommend looking into a library such as Jquery, which makes it a lot easier. See http://api.jquery.com/jquery.ajax/ This AJAX code will need a communication point on the server to send the file contents to. From your profile it seems you're familiar with PHP. You could make a php file on the server (say receivefilecontents.php) that takes in input from that client-side AJAX call, and then saves it to a server directory - you could also do this in Python, Java or a number of other languages.

Passing Value from C++ to Javascript

i have a c++ file which reads values from a sensor and I want to display those values on a website dynamically. So Im looking for a way to pass these values(integers) from my cpp file to an javascript which displays them on the site.
My first, simple try was to write the values into a js file as variables every second from my cpp script. The Js then uses this file as a source and displays its variables on the site:
cpp:
fprintf(file, "var mx=%d, my=%d, mz=%d, ax=%d, ay=%d, az=%d, gx=%d, gy=%d, gz=%d;\n",
imu.raw_m[0], imu.raw_m[1], imu.raw_m[2], // M = Magnetometer
imu.raw_a[0], imu.raw_a[1], imu.raw_a[2], // A = Accelerometer
imu.raw_g[0], imu.raw_g[1], imu.raw_g[2] // G = Gyroscope
);
html/js:
<script src="./imu.js" type="text/javascript"></script>
The Problem now is of course, that I need to refresh the page all the time, because the imu.js file is cached by the website.
I'd rather have a way to directly pass to integers from the cpp file to the js script. I read something about json or Googles V8 script. But I'd like to hear your suggestions first.
By the way, Im running this on a raspi, if this is important.
Thanks for your help
EDIT:
I'm goning to try it with a mysql database, in which my cpp file writes the data from the sensor with Connector/c++ from http://dev.mysql.com/doc/connector-cpp/en/ and my website reads them.
You could compile your C++ code into a Node.js plugin, you can then register a JavaScript function with your plugin which the C++ calls when it updates the value. That way you can pass values directly from C++ into Javascript in a managed and controlled way.
Node.js has the added benefit of being able to host your webpage and do all the Websocket and HTTP stuff that can be a pain in C++.
You do not have to refresh if your script is smart about how to access the data file! In case you do have a webserver at hand: Take care that your data file is accessible by your webserver and then let your script request the file via ajax (link to w3schools)
I'm doing something similar on a BeagleBone Black. With websocketd you can turn pretty much any program into a websocket endpoint and then send data via stdin and stdout commands. This would be a particularly good solution for you since websockets are designed to handle information that's constantly changing.

save as PDF: recommend a server solution to receive raw data from client and send back PDF to client?

My project requires me to add a "SaveAs PDF" feature. I was looking for a pure JavaScript solution which does this just in client end, however, was told that it's not implementable, at least for now.
jsPDF currently is still a limited version, not support graph and others. So now I am looking for a stable open-srouce free solution to set up a server web service, that receive data from client-end and send back the produced PDF file or a link for user to save to their disk.
The data from client is determined by client user, which means, not the whole page. User can choose to save a map, a table, or all of them into PDF file.
Any recommendations?
PS: in Windows environment
You might check out the ReportLab Toolkit - it includes an Open Source Python library for creating PDFs. (You didn't specify what server-side language you wanted, but Python is pretty widely supported.)
If you need something that can be coded in Javascript, one option might be PhantomJS. This tool allows you to run a headless Webkit browser from the command line, and among other things it can render and save webpages as PDFs. Slippy uses this approach, so you might be able to get example code from that project. Scripting the PDF creation would probably be much faster in PhantomJS than in Python, but it's likely to be much slower (it has to fire up a Webkit instance) and server installation might be complicated.
I've create this function in javascript which send on iframe to the server:
function download(url, datas){
if(url && datas){
var inputs = '', value,
iframe = '<iframe name="iframeDownload" id="iframeDownload" width=0 height=0></iframe>';
$(iframe).appendTo('body');
datas.forEach(function(data){
name = encodeURI(data.get('name'));
value = encodeURI(data.get('value'));
inputs+='<input name="'+name+'" value="'+value+'"/>';
});
$('<form action="'+url+'" method="post" target="iframeDownload">'+inputs+'</form>').appendTo('body').submit().remove(); // .appendTo and remove() are needed for firefox
$(iframe).remove();
};
};
I'm encoding the input name and value to be able to send data.
On my server, I'm using php, so to decode this, you need: rawurldecode. If you define the name of the inputs as "fileName" and "file" you can write this:
$fileName = rawurldecode($_POST['fileName']);
$file = rawurldecode($_POST['file']);
After than, to force the download, you need to send the corrects header. I'm using this function:
function download($filename, $file) {
header('Content-disposition: attachment; filename="'.$filename.'"');
header('Content-Type: application/force-download');
header('Content-Length: '. filesize($file));
readfile($file);
}
If you don't need to send the file from javascript because it's created on the server side, just add the path of your file to the download function.
If you're using PHP, You can use fpdf to generate the pdf.

How to read contents of a file using javascript?

I have an input type="file" button. After I choose a file, I have to read the contents of the file using javascript. Is it possible to read/get contents of a chosen file using javascript or ajax?
You are all wrong in a way. It is possible. With the new File API you can read files before submitting them to the server. It is not available in all browsers yet though.
Check this example. Try to open a text file for example.
http://development.zeta-two.com/stable/file-api/file.html
Edit: Even though the question states "uploaded file" I interpret it as, "a file to be uploaded". Otherwise it doesn't make sense at all.
With AJAX its possible to read uploaded file but with pure javascript its not possible because javascript works on client side not on sever side.
if you are going to use jquery than Ajax call may be like this
$.ajax({
url: "test.html",
context: document.body,
success: function(){
$(this).addClass("done");
}
});
Reading files client side is hard:
How to read and write into file using JavaScript
Read a local file
Local file access with javascript
Unless you are trying to do it with local javascript:
Access Local Files with Local Javascript
Or server side javascript:
http://en.wikipedia.org/wiki/Server-side_JavaScript
Alternatively you can force your user to install an ActiveX object:
http://4umi.com/web/javascript/fileread.php
you cant do it using javascript directly. You can post the file to the server an then use ajax to retrieve the content.
Javascript is designed not to have access to the computer it is running on. This is so that rogue javascript can't read the user's harddrive.
You could look into using iframes though.
It is not possible to do it in java script. See Local file access with javascript
I agree with DoXicK above. You can post the file first on server and then you can use Ajax to read it.
That is not entirely impossible
A browser's usually runs Javascript(JavaScript Engine) in a sandboxed environment.
So you can use Windows Scripting Host or Internet Explorer in a trusted environment and use the FileSystemObject
or use
Or upload a file to your server and use the XMLHttpRequest object.(in other words - Ajax)
For IE use the FileSystemObject (which is found on all Windows systems).
For Firefox:
var file = Components.classes["#mozilla.org/file/local;1"].
createInstance(Components.interfaces.nsILocalFile);
file.initWithPath("/home");
See https://developer.mozilla.org/en/Code_snippets/File_I%2F%2FO
To see these methods and others in use, look at TiddlyWiki app to see how it does it across all major browsers.

How to create a file using javascript in Mozilla Firefox

I want to write a function in javascript which creates a file and write some content to it, iam working with firefox, can anybody help me in this case.
Thanks...
You can write files in JavaScript in Firefox, but you have to use an XPCOM object (internal browser API). This is not allowed for JavaScript loaded from a web page, and it is intended to be used by JavaScript running inside a Firefox add-on (with high level of privileges).
There is a way for unprivileged (web page) JavaScript to request more privileges and if the user grants it (there will be a pop up dialog asking for permission), the web page code would be able to write to a file.
But before you read further, a warning:
This is not standard JavaScript and I would not recommend this approach unless you are developing a very specific application, that will be used in a very specific way (like for example, http://www.tiddlywiki.com/ a client-side JavaScript-HTML only wiki).
Requesting XPCOM privileges on a website is a bad practice! It's basicly equivalent to running an .exe you just downloaded from a site. You are asking a user to grant full access to their computer (read, write, execute) with the identity of the user running Firefox.
Request permission to use XPCOM (this will prompt the user for confirmation, no way to avoid it):
netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
Then, write to a file using an XPCOM object (example code from Mozilla Developer Network):
1. // file is nsIFile, data is a string
2. var foStream = Components.classes["#mozilla.org/network/file-output-stream;1"].
3. createInstance(Components.interfaces.nsIFileOutputStream);
4.
5. // use 0x02 | 0x10 to open file for appending.
6. foStream.init(file, 0x02 | 0x08 | 0x20, 0666, 0);
7. // write, create, truncate
8. // In a c file operation, we have no need to set file mode with or operation,
9. // directly using "r" or "w" usually.
10.
11. // if you are sure there will never ever be any non-ascii text in data you can
12. // also call foStream.writeData directly
13. var converter = Components.classes["#mozilla.org/intl/converter-output-stream;1"].
14. createInstance(Components.interfaces.nsIConverterOutputStream);
15. converter.init(foStream, "UTF-8", 0, 0);
16. converter.writeString(data);
17. converter.close(); // this closes foStream
You can find more information about I/O in Firefox using XPCOM here: https://developer.mozilla.org/en-US/docs/Code_snippets/File_I_O
Javascript from websites cannot access the local file system.
If you like to store data either store it on the server or in a cookie.
writing to the file system directly from a browser is prohibited for security reasons. With html5 however it'll be possible to have offline storage support. Take a look here.
Grz, Kris.
Javascript executes in a client-side context.
http://www.tek-tips.com/viewthread.cfm?qid=1171273&page=1
There will be an API for this.. File Writer API. The early specification is here:
http://www.w3.org/TR/file-writer-api/
It is not implemented in any browser yet.
Update: It seems there already exists an implementation. Check out http://caniuse.com/filesystem and http://www.html5rocks.com/en/tutorials/file/filesystem/
While everyone who's responded that javascript does not have the ability to write files on a remote server are correct, and this is true for security reasons, what you want to accomplish may still be possible.
For example, if you wanted to make it possible to create a file on your website with the use of javascript, you can do so with some server side scripting language and and AJAX call.
Example:
You have a file on your server called update_last_access.php which will create a file which stores the last time the file was accessed in some arbitrary file.
If you then had your javascript function make an AJAX call out to that script, for instance, in jquery
$.get("update_last_access.php")
Then this would execute the server side script and write to the file.
Before any more help can be provided for you, you're going to have to clarify what you're trying to do.
You can read files from the filesystem in JavaScript with Firefox 3.6 - see my EPUB reader proof of concept, for example.
You can't write files directly from JavaScript, though. You have to go via a server.
Mozilla is planning to include FileSaver to Gecko 9:
https://bugzilla.mozilla.org/show_bug.cgi?id=557540

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