Stripe.js error with Laravel - javascript

I seem to be having a problem with Stripe.js and I am using Laravel as a framework with cashier.
I'm using stripe.js so I don't pass and credit card data through my server and also so I don't store any either. As of the current time, there seems to be an issue with browsers. Let me explain further, Chrome works and Firefox, Internet Explorer doesn't.
On Chrome:
Currently when you submit the field, the form behaves as expected. It will show card errors when you press the submit button. For example, the card number, expire month, etc (it validates it).
On Firefox and IE:
The form will not verify, instead it says:
A network error has occurred, and you have not been charged. Please try again.
And will automatically submit the form and not tell if the card number is accepted, etc. Also when you submit the form, it goes straight to a Laravel error page that says:
Missing required param: card
and I think this means that the stripe.js is not fully being used, and maybe the form isn't paying attention the the custom js.
Stripe.js
$(document).ready(function() {
Stripe.setPublishableKey('pk_test_HdoLAxfuWl53vjchF01fMphS');
$('#subscription-form button').on('click', function() {
var form = $('#subscription-form');
var submit = form.find('button');
var submitInitialText = submit.text();
submit.attr('disabled', 'disabled').text('Just one moment...');
Stripe.card.createToken(form, function(status, response) {
var token;
if(response.error) {
form.find('.stripe-errors').text(response.error.message).show();
submit.removeAttr('disabled');
submit.text(submitInitialText);
return false;
} else {
token = response.id;
form.append($('<input type="hidden" name="token">').val(token));
form.submit();
}
});
});
});
You may go try out the app at http://account.mcjoin.us and better direct me with the possible issue. And always, thanks for the help!

The solution for my issue was quite obvious; Internet Explorer and Firefox have not depreciated the e.preventDefault();
This may be confusing, but let me explain. On Chrome, e.preventDefault() is not necessary, and what it does is prevent the default form function. On Internet Explorer or Firefox, if this is not present, Javascript will not be able to "hijack" the form and do what it needs to do. Therefor, adding e.preventDefault() will make it so that the form doesn't have the default interaction.
Let's look further into the code now, here is stripe.js:
$(document).ready(function() {
Stripe.setPublishableKey('pk_live_DdMQOXgak0v4yS0yH7vnsHqu');
$('#subscription-form button').on('click', function(e) {
var form = $('#subscription-form');
var submit = form.find('button');
var submitInitialText = submit.text();
submit.attr('disabled', 'disabled').text('Just one moment...');
e.preventDefault();
Stripe.card.createToken(form, function(status, response) {
var token;
if(response.error) {
form.find('.stripe-errors').text(response.error.message).show();
submit.removeAttr('disabled');
submit.text(submitInitialText);
} else {
token = response.id;
form.append($('<input type="hidden" name="token">').val(token));
form.submit();
}
});
});
});
That's it! It's just that simple!

I took a look at your page, but it requires authentication. I suspect you're getting this result because there's a JavaScript error that only occurs on Firefox and IE that prevents the Stripe.js code from working. I'd check the error console for that. Removing all other JavaScript that might be on the page and retesting would also confirm this theory.
I'd also update your server-side code so that no charge attempt is made without having a token present.
Cheers,
Larry
PS I work on Support at Stripe.

Related

Is there a way to detect if the browser has a mailto protocol handler set?

I have a site that dynamically builds a mailto url which it then opens in a new tab/window, using window.open().
window.open("mailto:" + encodeURIComponent(r["to"]));
I'm testing in Chrome at this stage, so other browsers may act differently.
If Chrome has a mailto protocol handler set up (e.g. GMail), then it works as expected.
If Chrome does not have a mailto protocol handler set up, it just opens a tab with the mailto url and nothing else.
That's not the worst result, but it would be nice if there was a way of knowing in advance, so that the user could be in some way guided to setting up their browser so that the mailto url worked nicely.
Previously, I was just opening in the same page by setting window.location.href to the url:
windows.location.href = "mailto:" + encodeURIComponent(r["to"]);
This wasn't great because if there was no protocol handler set, nothing happened. I also would consider this as an option, IF I can at least detect the situation, but wasn't able to find any indication of that either. I guess one option would be to set a timer which if it reached execution could alert the user?
Anyone else already solved this? Seems like a pretty common requirement.
Thanks
Here's what I ended up working with. It doesn't work in all cases, but provides at least some help in recognising unhandled protocols.
It attempts to open the URL in a new window and then after 2s it takes a look to see if it can read the location. If it has opened a third party site (e.g. GMail) this will raise and exception - so we treat this as success.
If no exception occurs, this returns "about:blank" which means we (probably) failed.
function openWin(url) {
return new Promise((resolve, reject) => {
const w = window.open(url);
if (!w) {
reject();
}
setTimeout(function() {
try {
const working = w.document.location.href;
} catch (e) {
resolve();
return;
}
w.close();
reject();
}, 2000);
});
}
Called with something like this:
openWin('mailto:' + encodeURIComponent(to)).then(() => {
// handle success
}).catch(() => {
// handle failure
});
Caveat: This only works for web-based protocol handlers. If for example your mailto is handled by an email app, then this will fail.
In my case, most people would be using web-based email, so it works for most cases. On failure I show a message to the affect of "If your email didn't open, copy the email address here..."

jQuery ajax get request not working with IE 11

I use this code to detect changes to a form and then perform a get request using the serialized form data. This works in all browsers that I have tested on. But I'm on a mac and now I get emails from people saying that it doesn't work in IE 11. What could be wrong?
Error message: "webpage.com is not responding due to a long running script"
I've tried testing this myself using IE 11 in a VirtualBox but the webpage becomes unresponsive as soon as I change something to the form. I'm not sure how to find out what's wrong.. I have no loops so I don't get why this script would make the page unresponsive.
Please help.
jQuery('.appselect').change(function(e) {
if (jQuery(window).width() > 800) {
jQuery.get('/?' + jQuery('#appfilter').serialize(), function(data) {
jQuery('#postloop').replaceWith( jQuery(data).find('#postloop') );
if (!jQuery('#pagination').length) {
jQuery('#postloop').after(jQuery(data).find('#pagination'));
} else {
jQuery('#pagination').replaceWith(jQuery(data).find('#pagination'));
}
});
}
});
This is a wordpress page, but I think the problem is not related to Wordpress. I'm using jQuery 1.11.1.
Try with:
var html = jQuery(data).find('#postloop').html();
jQuery('#postloop').html(html);

CasperJS- Register on a site and validate the mail sent on Gmail -for both slimer and phantom-

Edit : this is the windows behaviour, with linux it just fails.
First, if you succeeded navigate on gmail with casper (without random waiting time -from 20sec to 5min-), please tell me.
I want to register on our site, then validate my registration automatically with Gmail (an entire register step). Did someone do that before?
I have no problem to register, and I can login on my mailbox (Gmail) but after i have some troubles to navigate and validate my registration in Gmail, and i observe different behaviors between phantomJS and slimerJS.
In phantom it will work (without special commands), but it may take until 5 minutes before pass in the next step (waitForSelector). And with slimerjs it just stays stuck on the mailbox page.
EDIT : A strange thing : if i click manually (slimer) on a link which opens a popup, it stops being blocked and my navigation continues, it's like it can't detect the end of the step itself and can't perform the waitFor after the submit click without another interaction. Is it a refresh/reload problem?
Try that to see yourself :
casper.thenOpen('https://accounts.google.com/ServiceLogin?service=mail&continue=https://mail.google.com/mail/&hl=en', function(){
this.sendKeys("input#Email","your mail");
this.sendKeys("input#Passwd","your password");
this.click("input#signIn.rc-button-submit");
console.log(this.getCurrentUrl());
this.waitForSelector(".aeF",function(){//fail with linux -> timeout
this.test.pass("ok"); //windows -> stuck in slimer, several times in phantom
this.test.assertExists(".T-I.J-J5-Ji.T-I-KE.L3","Gmail Home ok");
console.log("url "+this.getCurrentUrl());
});
And i don't get any timeOut error. In slimerjs it just keeps the page opened.
If i do a waitForPopup instead of a waitForUrl, i have the error (timeout -> did not pop up), so why does a waitForUrl/waitForSelector... stay stuck ? I tried --web-security=no,--ignore-ssl-errors=true commands too (not linked but i tried --output-encoding=ISO 8859-1 too which doesn't work).
Here the differences between phantom and slimer (doc) :
http://docs.slimerjs.org/0.8/differences-with-phantomjs.html
(useless in this issue i think)
Well, we finally found a way to do it : the problem is by default gmail loop on ajax requests, to check some new mails, etc... see Page polls remote url, causing casper to block in step.
Fortunately google proposes a way to avoid that, using the simplified HTML version (you can for example use a special gmail address for your tests using this version) :
That way the script works as it should.
Bonus :
/*
* Click on an element specified by its selector and a part of its text content.
* This method resolves some problem as random space in textNode / more flexible too.
* Need to fix one bug though : when there is a tag in textContent of our selector.
*/
casper.clickSelectorHasText = function (selector, containsText){
var tmp = this.getElementsInfo(selector)
,i
,l
,bool=false
;
for (i=0,l=tmp.length;i<l; i++){
if(tmp[i].text && tmp[i].text.indexOf(containsText)!==-1){
this.clickLabel(tmp[i].text);
bool=true;
break;
}
}
casper.test.assert(bool, "clickSelectorHasText done, text and selector found -> click selector " + selector +" which contains text " + containsText);
};
casper.thenOpen('https://accounts.google.com/ServiceLogin?service=mail&continue=https://mail.google.com/mail/&hl=en', function scrapeCode(){
//log in
this.sendKeys("input#Email","your email");
this.sendKeys("input#Passwd","your password");
this.click("input#signIn.rc-button-submit");
//wait to redirect to our mailbox
this.waitForSelector("form[name='f']",function(){
//check main block
this.test.assertExists("form[name='f']","Gmail Home ok");
this.test.assertSelectorHasText("span", "Your gmail title message");
this.clickSelectorHasText("font", "one string which appears in font tag");
//wait inscription message appears
this.waitForSelector("div.msg",function(){
this.test.assertSelectorHasText("a","the message which activates your account--> in <a>");
});
})
//validate our account
.then(function(){
this.clickLabel("the message which activates your account--> in <a>");
this.waitForPopup(/mail/, function(){
this.test.pass("popup opened");
});
this.withPopup(/mail/, function(){
this.viewport(1400,800);
this.test.pass("With Popup");
//wait something on your website (for me selector .boxValid)
this.waitForSelector(".boxValid", function(){
/*
* Here your code after validation
*/
});
});
})
It might be possible to do it with normal gmail using event, see resource.received.

Detecting protocol handler with Javascript [duplicate]

I have created a custom URL protocol handler.
http://
mailto://
custom://
I have registered a WinForms application to respond accordingly. This all works great.
But I would like to be able to gracefully handle the case where the user doesn't have the custom URL protocol handler installed, yet.
In order to be able to do this I need to be able to detect the browser's registered protocol handlers, I would assume from JavaScript. But I have been unable to find a way to poll for the information. I am hoping to find a solution to this problem.
Thanks for any ideas you might be able to share.
This would be a very, very hacky way to do this... but would this work?
Put the link in as normal...
But attach an onclick handler to it, that sets a timer and adds an onblur handler for the window
(in theory) if the browser handles the link (application X) will load stealing the focus from the window...
If the onblur event fires, clear the timer...
Otherwise in 3-5seconds let your timeout fire... and notify the user "Hmm, looks like you don't have the Mega Uber Cool Application installed... would you like to install it now? (Ok) (Cancel)"
Far from bulletproof... but it might help?
There's no great cross-browser way to do this. In IE10+ on Win8+, a new msLaunchUri api enables you to launch a protocol, like so:
navigator.msLaunchUri('skype:123456',
function()
{
alert('success');
},
function()
{
alert('failed');
}
);
If the protocol is not installed, the failure callback will fire. Otherwise, the protocol will launch and the success callback will fire.
I discuss this topic a bit further here:
https://web.archive.org/web/20180308105244/https://blogs.msdn.microsoft.com/ieinternals/2011/07/13/understanding-protocols/
This topic is of recent (2021) interest; see https://github.com/fingerprintjs/external-protocol-flooding for discussion.
HTML5 defines Custom scheme and content handlers (to my knowledge Firefox is the only implementor so far), but unfortunately there is currently no way to check if a handler already exists—it has been proposed, but there was no follow-up. This seems like a critical feature to use custom handlers effectively and we as developers should bring attention to this issue in order to get it implemented.
There seems to be no straightforward way via javascript to detect the presence of an installed app that has registered a protocol handler.
In the iTunes model, Apple provides urls to their servers, which then provide pages that run some javascript:
http://ax.itunes.apple.com/detection/itmsCheck.js
So the iTunes installer apparently deploys plugins for the major browsers, whose presence can then be detected.
If your plugin is installed, then you can be reasonably sure that redirecting to your app-specific url will succeed.
What seams the most easy solution is to ask the user the first time.
Using a Javascript confirm dialog per example:
You need this software to be able to read this link. Did you install it ?
if yes: create a cookie to not ask next time; return false and the link applies
if false: window.location.href = '/downloadpage/'
If you have control of the program you're trying to run (the code), one way to see if the user was successful in running the application would be to:
Before trying to open the custom protocol, make an AJAX request to a server script that saves the user's intent in a database (for example, save the userid and what he wanted to do).
Try to open the program, and pass on the intent data.
Have the program make a request to the server to remove the database entry (using the intent data to find the correct row).
Make the javascript poll the server for a while to see if the database entry is gone. If the entry is gone, you'll know the user was successful in opening the application, otherwise the entry will remain (you can remove it later with cronjob).
I have not tried this method, just thought it.
I was able to finally get a cross-browser (Chrome 32, Firefox 27, IE 11, Safari 6) solution working with a combination of this and a super-simple Safari extension. Much of this solution has been mentioned in one way or another in this and this other question.
Here's the script:
function launchCustomProtocol(elem, url, callback) {
var iframe, myWindow, success = false;
if (Browser.name === "Internet Explorer") {
myWindow = window.open('', '', 'width=0,height=0');
myWindow.document.write("<iframe src='" + url + "'></iframe>");
setTimeout(function () {
try {
myWindow.location.href;
success = true;
} catch (ex) {
console.log(ex);
}
if (success) {
myWindow.setTimeout('window.close()', 100);
} else {
myWindow.close();
}
callback(success);
}, 100);
} else if (Browser.name === "Firefox") {
try {
iframe = $("<iframe />");
iframe.css({"display": "none"});
iframe.appendTo("body");
iframe[0].contentWindow.location.href = url;
success = true;
} catch (ex) {
success = false;
}
iframe.remove();
callback(success);
} else if (Browser.name === "Chrome") {
elem.css({"outline": 0});
elem.attr("tabindex", "1");
elem.focus();
elem.blur(function () {
success = true;
callback(true); // true
});
location.href = url;
setTimeout(function () {
elem.off('blur');
elem.removeAttr("tabindex");
if (!success) {
callback(false); // false
}
}, 1000);
} else if (Browser.name === "Safari") {
if (myappinstalledflag) {
location.href = url;
success = true;
} else {
success = false;
}
callback(success);
}
}
The Safari extension was easy to implement. It consisted of a single line of injection script:
myinject.js:
window.postMessage("myappinstalled", window.location.origin);
Then in the web page JavaScript, you need to first register the message event and set a flag if the message is received:
window.addEventListener('message', function (msg) {
if (msg.data === "myappinstalled") {
myappinstalledflag = true;
}
}, false);
This assumes the application which is associated with the custom protocol will manage the installation of the Safari extension.
In all cases, if the callback returns false, you know to inform the user that the application (i.e., it's custom protocol) is not installed.
You say you need to detect the browser's protocol handlers - do you really?
What if you did something like what happens when you download a file from sourceforge? Let's say you want to open myapp://something. Instead of simply creating a link to it, create a link to another HTML page accessed via HTTP. Then, on that page, say that you're attempting to open the application for them. If it doesn't work, they need to install your application, which they can do by clicking on the link you'll provide. If it does work, then you're all set.
This was a recommended approach for IE by Microsoft support
http://msdn.microsoft.com/en-us/library/ms537503%28VS.85%29.aspx#related_topics
"If you have some control over the binaries being installed on a user’s machine, checking the UA in script seems like a relevant approach:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent\Post Platform
" -- By M$ support
Every web page has access to the userAgent string and if you drop a custom post platform value, detecting this in javascript using navigator.userAgent is quite simple.
Fortunately, other major browsers like Firefox and Chrome (barring Safari :( ), do not throw "page not found" errors when a link with a custom protocol is clicked and the protocol is not installed on the users machine. IE is very unforgiving here, any trick to click in a invisible frame or trap javascript errors does not work and ends up with ugly "webpage cannot be displayed" error. The trick we use in our case is to inform users with browser specific images that clicking on the custom protocol link will open an application. And if they do not find the app opening up, they can click on an "install" page. In terms of XD this wprks way better than the ActiveX approach for IE.
For FF and Chrome, just go ahead and launch the custom protocol without any detection. Let the user tell you what he sees.
For Safari, :( no answers yet
I'm trying to do something similar and I just discovered a trick that works with Firefox. If you combine it with the trick for IE you can have one that works on both main browsers (I'm not sure if it works in Safari and I know it doesn't work in Chrome)
if (navigator.appName=="Microsoft Internet Explorer" && document.getElementById("testprotocollink").protocolLong=="Unknown Protocol") {
alert("No handler registered");
} else {
try {
window.location = "custom://stuff";
} catch(err) {
if (err.toString().search("NS_ERROR_UNKNOWN_PROTOCOL") != -1) {
alert("No handler registered");
}
}
}
In order for this to work you also need to have a hidden link somewhere on the page, like this:
<a id="testprotocollink" href="custom://testprotocol" style="display: none;">testprotocollink</a>
It's a bit hacky but it works. The Firefox version unfortunately still pops up the default alert that comes up when you try to visit a link with an unknown protocol, but it will run your code after the alert is dismissed.
You can try something like this:
function OpenCustomLink(link) {
var w = window.open(link, 'xyz', 'status=0,toolbar=0,menubar=0,height=0,width=0,top=-10,left=-10');
if(w == null) {
//Work Fine
}
else {
w.close();
if (confirm('You Need a Custom Program. Do you want to install?')) {
window.location = 'SetupCustomProtocol.exe'; //URL for installer
}
}
}
This is not a trivial task; one option might be to use signed code, which you could leverage to access the registry and/or filesystem (please note that this is a very expensive option). There is also no unified API or specification for code signing, so you would be required to generate specific code for each target browser. A support nightmare.
Also, I know that Steam, the gaming content delivery system, doesn't seem to have this problem solved either.
Here's another hacky answer that would require (hopefully light) modification to your application to 'phone home' on launch.
User clicks link, which attempts to launch the application. A unique
identifier is put in the link, so that it's passed to the
application when it launches. Web app shows a spinner or something of that nature.
Web page then starts checking for a
'application phone home' event from an app with this same unique ID.
When launched, your application does an HTTP post to your web app
with the unique identifier, to indicate presence.
Either the web page sees that the application launched, eventually, or moves on with a 'please download' page.

How to detect browser's protocol handlers?

I have created a custom URL protocol handler.
http://
mailto://
custom://
I have registered a WinForms application to respond accordingly. This all works great.
But I would like to be able to gracefully handle the case where the user doesn't have the custom URL protocol handler installed, yet.
In order to be able to do this I need to be able to detect the browser's registered protocol handlers, I would assume from JavaScript. But I have been unable to find a way to poll for the information. I am hoping to find a solution to this problem.
Thanks for any ideas you might be able to share.
This would be a very, very hacky way to do this... but would this work?
Put the link in as normal...
But attach an onclick handler to it, that sets a timer and adds an onblur handler for the window
(in theory) if the browser handles the link (application X) will load stealing the focus from the window...
If the onblur event fires, clear the timer...
Otherwise in 3-5seconds let your timeout fire... and notify the user "Hmm, looks like you don't have the Mega Uber Cool Application installed... would you like to install it now? (Ok) (Cancel)"
Far from bulletproof... but it might help?
There's no great cross-browser way to do this. In IE10+ on Win8+, a new msLaunchUri api enables you to launch a protocol, like so:
navigator.msLaunchUri('skype:123456',
function()
{
alert('success');
},
function()
{
alert('failed');
}
);
If the protocol is not installed, the failure callback will fire. Otherwise, the protocol will launch and the success callback will fire.
I discuss this topic a bit further here:
https://web.archive.org/web/20180308105244/https://blogs.msdn.microsoft.com/ieinternals/2011/07/13/understanding-protocols/
This topic is of recent (2021) interest; see https://github.com/fingerprintjs/external-protocol-flooding for discussion.
HTML5 defines Custom scheme and content handlers (to my knowledge Firefox is the only implementor so far), but unfortunately there is currently no way to check if a handler already exists—it has been proposed, but there was no follow-up. This seems like a critical feature to use custom handlers effectively and we as developers should bring attention to this issue in order to get it implemented.
There seems to be no straightforward way via javascript to detect the presence of an installed app that has registered a protocol handler.
In the iTunes model, Apple provides urls to their servers, which then provide pages that run some javascript:
http://ax.itunes.apple.com/detection/itmsCheck.js
So the iTunes installer apparently deploys plugins for the major browsers, whose presence can then be detected.
If your plugin is installed, then you can be reasonably sure that redirecting to your app-specific url will succeed.
What seams the most easy solution is to ask the user the first time.
Using a Javascript confirm dialog per example:
You need this software to be able to read this link. Did you install it ?
if yes: create a cookie to not ask next time; return false and the link applies
if false: window.location.href = '/downloadpage/'
If you have control of the program you're trying to run (the code), one way to see if the user was successful in running the application would be to:
Before trying to open the custom protocol, make an AJAX request to a server script that saves the user's intent in a database (for example, save the userid and what he wanted to do).
Try to open the program, and pass on the intent data.
Have the program make a request to the server to remove the database entry (using the intent data to find the correct row).
Make the javascript poll the server for a while to see if the database entry is gone. If the entry is gone, you'll know the user was successful in opening the application, otherwise the entry will remain (you can remove it later with cronjob).
I have not tried this method, just thought it.
I was able to finally get a cross-browser (Chrome 32, Firefox 27, IE 11, Safari 6) solution working with a combination of this and a super-simple Safari extension. Much of this solution has been mentioned in one way or another in this and this other question.
Here's the script:
function launchCustomProtocol(elem, url, callback) {
var iframe, myWindow, success = false;
if (Browser.name === "Internet Explorer") {
myWindow = window.open('', '', 'width=0,height=0');
myWindow.document.write("<iframe src='" + url + "'></iframe>");
setTimeout(function () {
try {
myWindow.location.href;
success = true;
} catch (ex) {
console.log(ex);
}
if (success) {
myWindow.setTimeout('window.close()', 100);
} else {
myWindow.close();
}
callback(success);
}, 100);
} else if (Browser.name === "Firefox") {
try {
iframe = $("<iframe />");
iframe.css({"display": "none"});
iframe.appendTo("body");
iframe[0].contentWindow.location.href = url;
success = true;
} catch (ex) {
success = false;
}
iframe.remove();
callback(success);
} else if (Browser.name === "Chrome") {
elem.css({"outline": 0});
elem.attr("tabindex", "1");
elem.focus();
elem.blur(function () {
success = true;
callback(true); // true
});
location.href = url;
setTimeout(function () {
elem.off('blur');
elem.removeAttr("tabindex");
if (!success) {
callback(false); // false
}
}, 1000);
} else if (Browser.name === "Safari") {
if (myappinstalledflag) {
location.href = url;
success = true;
} else {
success = false;
}
callback(success);
}
}
The Safari extension was easy to implement. It consisted of a single line of injection script:
myinject.js:
window.postMessage("myappinstalled", window.location.origin);
Then in the web page JavaScript, you need to first register the message event and set a flag if the message is received:
window.addEventListener('message', function (msg) {
if (msg.data === "myappinstalled") {
myappinstalledflag = true;
}
}, false);
This assumes the application which is associated with the custom protocol will manage the installation of the Safari extension.
In all cases, if the callback returns false, you know to inform the user that the application (i.e., it's custom protocol) is not installed.
You say you need to detect the browser's protocol handlers - do you really?
What if you did something like what happens when you download a file from sourceforge? Let's say you want to open myapp://something. Instead of simply creating a link to it, create a link to another HTML page accessed via HTTP. Then, on that page, say that you're attempting to open the application for them. If it doesn't work, they need to install your application, which they can do by clicking on the link you'll provide. If it does work, then you're all set.
This was a recommended approach for IE by Microsoft support
http://msdn.microsoft.com/en-us/library/ms537503%28VS.85%29.aspx#related_topics
"If you have some control over the binaries being installed on a user’s machine, checking the UA in script seems like a relevant approach:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent\Post Platform
" -- By M$ support
Every web page has access to the userAgent string and if you drop a custom post platform value, detecting this in javascript using navigator.userAgent is quite simple.
Fortunately, other major browsers like Firefox and Chrome (barring Safari :( ), do not throw "page not found" errors when a link with a custom protocol is clicked and the protocol is not installed on the users machine. IE is very unforgiving here, any trick to click in a invisible frame or trap javascript errors does not work and ends up with ugly "webpage cannot be displayed" error. The trick we use in our case is to inform users with browser specific images that clicking on the custom protocol link will open an application. And if they do not find the app opening up, they can click on an "install" page. In terms of XD this wprks way better than the ActiveX approach for IE.
For FF and Chrome, just go ahead and launch the custom protocol without any detection. Let the user tell you what he sees.
For Safari, :( no answers yet
I'm trying to do something similar and I just discovered a trick that works with Firefox. If you combine it with the trick for IE you can have one that works on both main browsers (I'm not sure if it works in Safari and I know it doesn't work in Chrome)
if (navigator.appName=="Microsoft Internet Explorer" && document.getElementById("testprotocollink").protocolLong=="Unknown Protocol") {
alert("No handler registered");
} else {
try {
window.location = "custom://stuff";
} catch(err) {
if (err.toString().search("NS_ERROR_UNKNOWN_PROTOCOL") != -1) {
alert("No handler registered");
}
}
}
In order for this to work you also need to have a hidden link somewhere on the page, like this:
<a id="testprotocollink" href="custom://testprotocol" style="display: none;">testprotocollink</a>
It's a bit hacky but it works. The Firefox version unfortunately still pops up the default alert that comes up when you try to visit a link with an unknown protocol, but it will run your code after the alert is dismissed.
You can try something like this:
function OpenCustomLink(link) {
var w = window.open(link, 'xyz', 'status=0,toolbar=0,menubar=0,height=0,width=0,top=-10,left=-10');
if(w == null) {
//Work Fine
}
else {
w.close();
if (confirm('You Need a Custom Program. Do you want to install?')) {
window.location = 'SetupCustomProtocol.exe'; //URL for installer
}
}
}
This is not a trivial task; one option might be to use signed code, which you could leverage to access the registry and/or filesystem (please note that this is a very expensive option). There is also no unified API or specification for code signing, so you would be required to generate specific code for each target browser. A support nightmare.
Also, I know that Steam, the gaming content delivery system, doesn't seem to have this problem solved either.
Here's another hacky answer that would require (hopefully light) modification to your application to 'phone home' on launch.
User clicks link, which attempts to launch the application. A unique
identifier is put in the link, so that it's passed to the
application when it launches. Web app shows a spinner or something of that nature.
Web page then starts checking for a
'application phone home' event from an app with this same unique ID.
When launched, your application does an HTTP post to your web app
with the unique identifier, to indicate presence.
Either the web page sees that the application launched, eventually, or moves on with a 'please download' page.

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