Binding to OPOS MSR DataEvent with JavaScript? - javascript

I have implemented an MSR OPOS ActiveX control for use in an IE-based web application. I have tested the device and it works; however, I'm trying to port the VBScript code found here to JavaScript for easier maintainability.
I'm having trouble binding to the DataEvent with JavaScript though -- when I put the card to the reader, the data definitely appears to take, as I can query the object directly through the console with ReaderControl.Track1Data and see that there is in fact data there.
In the VBScript version, there seems to be a method called [control]_DataEvent that you can simply override in order to bind to the event. I have tried ReaderControl.attachEvent("DataEvent", function() { alert(ReaderControl.Track1Data); }), which does seem to work, for some reason, only when subsequently set ReaderControl.DataEventEnabled = true;.
Any ideas?

Related

Use content script to define global variables

I am creating a Firefox extension, and one feature of it that I would like is the ability for the user to inject a script or stylesheet into a specific website, rather like Greasemonkey (except that this will only be for one site). I am adding some functions for the scripts to make use of, which I intended to add from the Content Script into the main (unsafe) window. On the MDN blog, it says that they have made changes to how it should be implemented, so I have based my code on the new implementation as advised in the post, so this is what I have:
var $jq = jQuery.noConflict();//Yes, I am also injecting jQuery at the same time
console.log("created jquery object"); //This works
exportFunction($jq, unsafeWindow, {defineAs: "$jq"});
console.log("This will never be called");
But execution of the script just stops, and in the console it prints Message: TypeError: window is null.
I am testing in Firefox 28 predominantly (I can't seem to get Firefox for Ubuntu to update beyond that right now, and a whole load of issues are forcing me to use Ubuntu in a VM for this), but in Nightly 31a1 (Win7) nothing is ever injected, including a hardcoded style (that works on FF28) so I will have to figure that out at some point. (The PageMod code is here:
var lttWorker = sdk.pageMod.PageMod({
include:["*"],
/*contentScriptFile: [sdk.data.url("jquery.large.js"), sdk.data.url("scripts/bootstrapper.js")],
contentScriptWhen: "ready",*/ //This is commented to test whether it was an issue with the script. It's not.
contentStyle: "#header_bar{background-color:green;}", //This is injected in FF28 but not 31
attachTo: ["existing", "top"],
onAttach: function(){desktopNotifications({title:"attached content worker", text:"The content worker has been successfully attached"})} //This is called in FF28 but not 31
});
lttWorker.on("error", function(){callError("pageWorker failed");}); //This never gets called. Ever.
if anybody is interested)
EDIT: I have now tried it on Firefox 30b and there are still a load of issues, although they seem to be slightly different to both FF28 and 31...
First of all: These new functions are supported in Firefox 30 and later. See #canuckistani answer.
The exportFunction API is way too limited to actually inject something like jQuery with all the complex objects being or containing DOM nodes. That simply won't fly with the structured-clone algorithm that is applied to arguments.
The API is meant as a way for add-ons to communicate with pages bi-directionally, and not to inject complex libraries.
Your best bet is actually creating a script tag using the DOM APIs and putting jQuery there.

Is it possible to make an object created in console persistent throughout the session?

Goal: making a standalone modular JavaScript debuggin-utility (includes custom dom and event manipulation methods) to be used in the console (preferably Chrome) on any random sites of interests (with no backend access).
Usage: initially include module script directly via copy-paste to console or by creating a new script element pointing at myhomepage.com/shortandeasytoremember.js and call methods on the namespace from there on.
Problem: how to best make it persistent throughout the session on that webpage (so that I wouldn't need to reinclude it after every refresh) ?
Note: any additional browser compatibility is not required - as long as it works in the latest Chrome, it's all fine by me (but any effort in the compatibility department is always much appreciated for the sake of others). IF YOU READ THIS IN A FAR FUTURE and by then there exists a better solution than what is written down below, please take a moment to contribute with your superior knowledge.
What I currently have is an event listener on window.unload to save any state data to localStorage and a string to make it easier to reinclude the module after page reload using eval(localStorage.getItem('loadMyNS'));.
(function(ns, undefined){
'use strict';
//util methods on ns and few monkey patches for debugging ...
var store = 'if(!window.MyNS){' +
'var xyz9=document.createElement("script");' +
'xyz9.src="http://myhomepage.com/shortandeasytoremember.js";' +
'document.head.appendChild(xyz9);}';
localStorage.setItem('loadMyNS', store);
ns.save = function () {
// and use localStorage for some more data
// to be used by other methods after page reload
};
window.addEventListener('unload', ns.save, false);
}(window.MyNS = window.MyNS || {}));
(browsers with no localStorage or addEventListener may benifit from this article)
I've also concidered using the same schema with window.name instead of localStorage (as long as this still seems legid) just because writing eval(window.name) would take less typing ^^.
The trouble (one of them) I have with the "eval-script-tag-inclusion" is on the sites which block external non-https script sources. An ideal solution would be a globally accessible module which would live with state and methods included (and no initialization required after refresh) at least until I close the the window (or overwrite the ref ofc).
If that is currently absolutely not possible, a lesser solution yet still superior to my current code would suffice.

Setting breakpoints dynamically at runtime in Javascript

Both firebug and the built in console in webkit browsers make it possible to set breakpoints in running Javascript code, so you can debug it as you would with any other language.
What I'm wondering is if there is any way that I can instruct firebug or webkit that I'd like to set a breakpoint on line X in file Y at runtime, and to be able to examine variables in the specific scope that I have paused in.
I need something that can work in both Chrome (or any other webkit browser) and Firefox. For the latter Firebug is an acceptable dependency. Supporting IE is not a requirement.
I've been building an in-browser IDE ( quick video for the interested: http://www.youtube.com/watch?v=c5lGwqi8L_g ) and want to give it a bit more meat.
One thing I did try was just adding debugger; as an extra line where users set them, but this isn't really an ideal solution.
I'd say you can definitely do this for webkit browsers using the remote debugging protocol. This is based on a websocket connection and a json message protocol that goes back and forth.
You can read the announcement and the whole protocol schema.
Chrome also offers more information about this inside its remote developer-tools docs.
For the debugger domain, for instance, you can see how you can use Debugger.setBreakpoint, Debugger.setBreakpointByUrl and Debugger.setBreakpointsActive to work with breakpoints.
On the other hand, Mozilla also seems to be working on this as you can see in https://developer.mozilla.org/en-US/docs/Tools/Debugger-API and https://wiki.mozilla.org/Remote_Debugging_Protocol though I don't know the completion status of it.
In this case, you can work with breakpoints using the Debugger.Script APIs setBreakPoint, getBreakPoint, getBreakpoints, clearBreakpoints and clearAllBreakpoints
I hope this helps you move forward.
There isn't such a thing, at least not using the public, scriptable side of JavaScript. It would be possible if you have a privileged browser extension that could do that for you. For example, Firebug has a debug method which you can call from its command line, but not from scripts inside a page.
So, you have two solutions:
Implement your own JavaScript interpreter, which you can control as you wish. Might be a bit too ambitious, though...
Rely on a browser extension that can set breakpoints anywhere in the code, expose some API to public code, and interact with it from your JavaScript. But that means that users will have to install some extra piece of software before they can use your "Web IDE".
Use _defineSetter__ to watch variables, and combine it with a call to debugger when an assignment happens.
__defineSetter__("name", function() { debugger; });
or defineProperty:
function setter () { debugger; }
Object.defineProperty(Math, 'name', { set: setter });
References
MDN: Object.defineProperty
A List Apart: Advanced Debugging With JavaScript
JavaScript Getters and Setters

Strange Javascript/vbscript behavior when opening file from browser

An old web application I recently have to work with is having an issue. There is an input element that contains the following:
onClick="javascript:Run('**SomeFilePath.mdb**');"
What this is supposed to do is open a users respective .mdb file.
First off, there is no javascript Run function defined anywhere. I searched online because I thought maybe it's an old javascript built-in, but I couldn't find anything.
Second off, there IS a vbscript Run() function, that implements the described behavior, defined in the source code, but as far as I know javascript can't call that other than via ajax, which as you can see isn't what is happening.
The strange part is this works for some users!
If anyone could shed some light as to why I'd appreciate it!
EDIT: The only browser I'm dealing with is IE. I know there is an active-x way to open a file, which is what the vbscript Run() function I mentioned above is using.
Update: So after more investigation/research, it would seem like when IE doesn't find the javascript Run() function it defaults to the vbscript Run() function that IS defined. However this only occurs on some versions of IE. Can anyone confirm this behavior?
Research links:
Comment referring to how IE defaults w/ scripting
Msdn article about using both script types in same page
Yes, you can run vbscript from javascript and vice-versa, i do it sometimes when one language doesn't support something the other does.
You can indicate in your script which is the default language in case you don't specify it like .
You can also specify it while calling the function like vbscript:functionname("..") or javascript:functionname("..")
As you noticed there are cases where the browser gets confused and doesn't find the function because he searches/executes the function in the wrong language.
This behavior is influenced i suppose by version also but surely by in which order the logic flows in your script, if the browser first executes a javascript he tends to go further in this language in case of doubt.
So to evade this
don't mix the two unless realy necessary, translate your vbscript function in javascript)
try to always use javascript, vbscript is less good at handling DOM etc
in case they are mixed, specify the correct scriptlanguage when you call a function
when opening a script tag, also give the correct language like or
So, specific, to solve your problem translate the vbsripts function to javascript and if not possible, call your function like onClick="vbscript:Run('**SomeFilePath.mdb**')"

Silverlight 4 MVVM: Call Javascript function from viewmodel

we have developed an Intranet Management Application with Silverlight 4. We have been asked to add the functionality to call a remote desktop tool which is installed on clients using the Intranet SL App. In an earlier version of the tool written in ASP.NET we just added a Javascript function to the aspx page like this:
function RunShellCommand()
{
var launcher = new ActiveXObject("WScript.Shell");
launcher.Run("mstsc.exe");
}
and called it from ASP.NET.
Now it's clear that SL4 is running in a sandbox and that I cant use the AutomationFactory to create a WScript.Shell object (out of browser mode is not an option).
I thought I could circle around the problem by, again, adding the RunShellCommand javascript method in the aspx page where the SL4 control is hosted and call it via
HtmlPage.RegisterScriptableObject("Page", this);
HtmlPage.Window.Invoke("RunShellCommand", "dummydata");
from my ViewModel. When I run the Application the debugger just skips the RegisterScriptableObject method and quits. Nothing happens.
My question is if am doing something wrong or if this just wont work this way.
Is it possible that I cant do a RegisterScriptableObject from a viewmodel?
EDIT: When I explicitly put a try, catch block around the two methods I get an ArgumentException from the first method stating that the current instance has no scriptable members. When I delete the first method and only run the Invoke, I get a browser error stating that the automation server cant create the object. So is there really no way (except OOB mode) to do this?
Yes, the explanation is correct: you should add at least one method with the ScriptableMember attribute in order that you can use the RegisterScriptableObjectmethod. But it is used only for calling C#-methods from JavaScript.
As far as I see, you want to do the opposite: to call JavaScript code from the Silverlight application. Then you need only one line:
HtmlPage.Window.Invoke("RunShellCommand");
The error automation server cant create the object has nothing to do with Silverlight. I'm sure that if you call the JS function directly - the error will remain.
According to the internet, the reason might be not installed Microsoft Windows Script. Or it is because of security restrictions of the browser.

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