Develop Reference

Getting access to a XML from javascript without Node-Without JQuery

I am trying to developp modifications to a game. The thing is the game is already compiled and the developpers prefer not to decompile the game (for the time beeing). Because of the compilation probably, everytime I try to load JQuery or Node.js whatever version I get the error "that a key already exists in the dictionary". The thing is everything is fine without Node.js or JQuery.js.
What I am trying to achieve is add some features to the game that unfortunately aren't available through the Game's API function call itself. I want to be able to get access to data Inside .xml files used for items/weapons/devices/engines spécifications of items Inside the game. I've tried pretty much all I could find on Stackexchange with what I searched for which was Node and JQuery. Im sorry if you guys think this is a duplicate question. Because it isn't. I can't use Node.js neither can i use JQuery. What else could I try? can someone help me please.
I am a bit new to programing with only 1 year experience in c# and Javascript. Sorry if this feels really noObish to you guys.

What you need is ajax. Modern browsers provide a pretty functional XMLHttpRequest, so you don’t even need a framework anymore.
One important thing to know: you most likely won’t be able to download the xml file using ajax if it’s on a distant server, due to the same-origin policy. You need a reliable access to it. The most convenient solution is to have a copy of the file on a local server such as WAMP, XAMPP, and the like.
I’m not going to write yet another ajax tutorial. Insteal I’ll just provide you with a working minimal HTML page, and point you towards XMLHttpRequest documentation.
<button>Request</button>
<script>
'use strict';
document.querySelector('button').addEventListener('click',
function () {
let req = new XMLHttpRequest();
req.onload = function () {
if (this.responseXML) {
console.log(this.responseXML);
}
else {
console.log(this.responseText);
}
};
req.open('GET', xmlURL); // xmlURL should be the location of the .xml file
req.send();
});
</script>
When you click on the button, the script will request, and then display the server’s response, if any, in your browser console. To open the console, press F12 and select the console tab.
Be aware that the responseXML property will only be populated if the xml sent by the server is strictly well-formed. Xml parsing in JS is somewhat finicky, so you may want to rely on responseText as a fallback.

Swift Headless WKWebView; running XMLHttpRequest

How can I run an XMLHttpRequest from within a WKWebView that I have created in Swift?
Currently, I use the WKWebView to access a page on a server I own. This page contains my Javascript. However, when I attempt to make an XMLHttpRequest by using WKWebView.evaluateJavaScript (i.e. call a javascript function that makes an XMLHttpRequest) the Javascript code executes successfully but the Safari debugger shows "Failed to load resource".
However, if I 'manually' make an XMLHttpRequest by using the console in the Safari debugger and then call my request function from my app, it works fine - but only once!
I'm at a bit of a loss as to why this is...
As mentioned in the comments, a better solution than bundling the Javascript with my swift library is to host the scripts on a page that is accessed via the WKWebView. Previous information maintained below;
Some background: I have been tasked with producing a Swift library that wraps our current Javascript API. I had hoped to use a WKWebView to simply load and execute our existing javascript code, however any XMLHttpRequests that I run simply return error (fire the onerror callback) instantly. The error object returned to onerror is {"position":0,"totalSize":0}
This thread seems to suggest that my WKWebView needs a 'parent' in order to execute javascript correctly. I have attempted to reproduce their code in Swift, but to no effect (see below)
let webConf = WKWebViewConfiguration()
WKWebView webView = WKWebView(frame: CGRectZero, configuration: webConf)
UIApplication.sharedApplication().keyWindow?.addSubview(webView)
In order to get to this point, I have had to set 'App Transport Security Settings -> Allow Arbitrary Loads' to 'YES' in my info.plist file, in order to enable non-https requests.

Chrome extensions for silent print?

I have made a silent print web application that prints a PDF file. The key was to add JavaScript to the PDF file that silently print itself.
To do this I open the PDF with acrobat reader in chrome, that allow me to execute the script (with the proper permissions).
But as it was announced this solution won't work after chrome 45 because the npapi issue.
I guess a possible solution could be to use the recently release printProvider of chrome extensions.
Nevertheless I can't imagine how to fire any of the printProvider events.
So the question is: Is ok to think in chrome extensions to make a silent print web application, and how can I fire and handle a print job for an embedded PDF of a HTML Page.

Finally I reached an acceptable solution for this problem, as I couldn't find it out there, but read to many post with the same issue I will leave my solution here.
So first you need to add your printer to the Google Cloud Print and then you will need to add a proyect to the Google Developers Console
Then add this script and any time you need to print something execute the print() function. This method will print the document indicated in the content
The application will ask for your permission once to manage your printers.
function auth() {
gapi.auth.authorize({
'client_id': 'YOUR_GOOGLE_API_CLIENT_ID',
'scope': 'https://www.googleapis.com/auth/cloudprint',
'immediate': true
});
}
function print() {
var xhr = new XMLHttpRequest();
var q = new FormData()
q.append('xsrf', gapi.auth.getToken().access_token);
q.append('printerid', 'YOUR_GOOGLE_CLOUD_PRINTER_ID');
q.append('jobid', '');
q.append('title', 'silentPrintTest');
q.append('contentType', 'url');
q.append('content',"http://www.pdf995.com/samples/pdf.pdf");
q.append('ticket', '{ "version": "1.0", "print": {}}');
xhr.open('POST', 'https://www.google.com/cloudprint/submit');
xhr.setRequestHeader('Authorization', 'Bearer ' + gapi.auth.getToken().access_token);
xhr.onload = function () {
try {
var r = JSON.parse(xhr.responseText);
console.log(r.message)
} catch (e) {
console.log(xhr.responseText)
}
}
xhr.send(q)
}
window.addEventListener('load', auth);
<script src="https://apis.google.com/js/client.js"></script>
Anyway this script throw a 'Access-Control-Allow-Origin' error, even though this appears in the documentation... I couldn't make it work :(
Google APIs support requests and responses using Cross-origin Resource Sharing (CORS). You do not need to load the complete JavaScript client library to use CORS. If you want your application to access a user's personal information, however, it must still work with Google's OAuth 2.0 mechanism. To make this possible, Google provides the standalone auth client — a subset of the JavaScript client.
So to go throw this I had to install this chrome extension CORS. I'm sure that some one will improve this script to avoid this chrome extension.

You can register an Application to a URI Scheme to trigger the local application to print silently. The setting is pretty easy and straightforward. It's a seamless experience. I have posted the solution here with full example:
https://stackoverflow.com/a/37601807/409319

After the removal of npapi, I don't believe this is possible solely programmatically. The only current way I know to get chrome to print silently is using chrome kiosk mode, which is a flag (mode) you have to set when starting chrome.
Take a look at these SO posts:
Silent printing (direct) using KIOSK mode in Google Chrome
Running Chrome with extension in kiosk mode

This used to be possible using browser plugins (e.g. Java + NPAPI, ActiveX) but has been blacklisted by most browsers for several years.
If interested in modern solutions that use similar techniques, the architecture usually requires the following:
WebSocket, HTTP or Custom URI connection back to localhost
API that talks through web transport (JavaScript or custom URI scheme) to an app running locally.
A detail of projects (several of them are open source) that leverage these technologies are available here:
https://stackoverflow.com/a/28783269/3196753
Since the source code of these projects can vary (hundreds of lines to tens-of-thousands of lines), a code snippet would be too large unless a inquiring about a specific project's API.
Side note: Some technologies offer dedicated cloud resources, which add convenience at the expense of potential latency and privacy. At the time of writing this, the most popular "free" cloud solution -- Google Cloud Print -- is slated to be retired in December 2020.

Log JavaScript console into a log file with Firefox

We have a web application which runs in a kiosk mode Firefox, using the RKiosk extension to achieve this. We suspect that we have a very rare error in the system which yields in a JavaScript error. However because we can't access the JavaScript console we can't examine the log.
I'm searching for an option to make Firefox log all JavaScript console messages into a file regardless of the tab and page opened. I can't seem to find any extension for this. I'm already using log4javascript which sends errors back to the server, but it seems that our application crashes in a way that it skips the logging altogether.

Writing to a file sounds like a tedious task to me. It requires privileges that browser code doesn't normally have and you'd have to negotiate with an add-on you'd have to write in order to access file I/O.
From what I understand your issue is
I'd like to make Firefox log all errors
There are several approaches we can do to tackle this
First approach - log everything to localStorage too:
Now, rather than writing to an actual file, you can write to localStorage or IndexedDB instead.
localStorage["myApplog"] = localStorage["myApplog"] || "";
var oldLog = console.log;
console.log = function(){
oldLog.apply(console,arguments); // use the old console log
var message = "\n "+(new Date).toISOString() + " :: "+
Array.prototype.join.call(arguments," , "); // the arguments
localStorage["myApplog"] += message;
}
This is rather dirty and rather slow, but it should get the job done and you can access the log later in local storage. LocalStorage has a ~5MB limit if I recall correctly which I think is enough if you don't go crazy with logging. You can also run it selectively.
Second approach - log only errors
This is similar to what Pumbaa80 suggested. You can simply override window.onerror and only log errors.
// put an empty string in loggedWinErrors first
var oldError = window.onerror || function(){};
window.onerror = function(err,url,lineNumber){
oldError.call(this,err,url,lineNumber);
var err ="\n Error: (file: " + url+", error: "+err+", lineNumber: "+lineNumber+")");
localStorage["loggedWinErrors"] += err;
}
Third and drastic approach - use a VM.
This is the most powerful version, but it provides the most problematic user experience. You run the kiosk in a virtual machine, you detect an uncaught exception - when you do you freeze the machine and save its state, and run a backup VM instead. I've only had to do this when tackling the most fearsome errors and it's not pretty. Unless you really want the whole captured state - don't do this.
Really, do the extension before this - this is tedious but it gets very solid results.
In conclusion, I think the first approach or even just the second one are more than enough for what you need. localStorage is an abstracted storage that web pages get for saving state without security issues. If that's not big enough we can talk about an IndexedDB solution.
It all really depends on the use case you have.

You can use XULRunner...a Mozilla runtime environment for XUL applications. It uses Gecko like Firefox and:
You can access the file system or using the SQLite database to store logs.
You can render your kiosk in fullscreen mode without using extensions.

Have you tried jserrorcollector? We are using it and it works fine (only in Firefox). It's only for Java.
// Initialize
FirefoxProfile ffProfile = null;
ffProfile = new FirefoxProfile();
JavaScriptError.addExtension(ffProfile);
// Get the errors
List<JavaScriptError> jsErrors = JavaScriptError.readErrors(webDriver);
More information: https://github.com/mguillem/JSErrorCollector

Have you considered remote logging?
I commonly assign window.onerror to do send a request to a webserver storing the details of the error remotely. You could do the same with console.log if you preferred.

Try the following console export. It is a plugin for Firebug of Firefox. It's quite handy.
http://www.softwareishard.com/blog/consoleexport/

If you are able/willing to switch from Firefox to Chrome or Opera you would be able to use the Sandboxed Filesystem API to write a local file. See:
http://www.html5rocks.com/en/tutorials/file/filesystem/
http://caniuse.com/filesystem
Start in kiosk mode using chrome.exe --kiosk <url>
You would then want to disable Alt-F4 and Ctrl-Alt-Del which on Windows can be done with several third-party tools like Auto Hotkey (Disable Ctrl-Alt-Del Script).

You could use a remote logging script like Qbaka. It catches every JS error and sends it to the Qbaka server. There you can login and see all JS errors. Qbaka stores the exact error message, the script, line number, stack trace and the used browser for each error message.

Is it possible to check if a file exists on disk using Javascript (not running in a browser)?

I am using an app that uses only JavaScript as its scripting language. I have a .ini file and I need to see if it exists. Is this possible?
Also, if it doesn't exist, how can I halt the execution?

Ok doing something like this works:
var file = new File(datafile);
var result = file.open ('r');
if result is true, then the file exists, otherwise false means the file does not exist.

"Yes", assuming ActiveX can be used.
See FileSystemObject aka "FSO" (the FileExists method in particular). FSO is part of Windows Scripting.
It is also possible to use the MSXML load method to access a "file://" and catch the appropriate error. (I don't know if a vanilla XmlHttpRequest request of "file://" can be used here, and/or in what contexts... it might differ between the XHR from MSXML and the one baked into IE7/8 as well.)
Happy coding.
If the JavaScript runs from an HTA/HTML Aplication or Windows Sidgebar Gadget, etc, then it's in "Security Level 0" or "Demigod Mode".
On the other hand, an HTA runs as a fully trusted application and therefore has more privileges than a normal HTML file...

Try this:
var myfile = new File(myfile_path);
if (!myfile.exists) {
alert(myfile + " could not be found!");
}