I have a WinForms app that uses a .NET webbrowser control. What I need to do, is wire up an event on the WinForms side to fire when a value is set (via javascript) in the loaded HTML page. I had success doing this with an onclick event of a button, but I can't seem to get it to work with a custom event. I don't know if this is a limitation in what the browser control can attach to event wise.
So essentially, I need that when a JS function is called in the HTML page and sets a value of a hidden input element (or it could be a regular input that I style to be hidden), I need to know that in WinForms. If it helps, I am using browser flags in this application to emulate IE11 instead of the default IE9 engine. The HTML page loaded is also mine so I can modify it any way needed to make this work properly. I would just use the onclick events of the buttons, but this is a gmaps integration where there can be upwards of 2000 buttons generated (one per marker placed) so it seems like a huge waste of resources to wire up 2000 onclick events when any of those button clicks only modify 4 input fields with the data I care about.
This project happens to be in VB.NET, but C# solutions would be fine as well. They can be transcoded or if the solution uses C# specific features, we can move this to a separate DLL and reference it.
After spending a lot of time on this today, I found a solution. It isn't a direct solution to the problem I posted, but it got me to where I needed to be. I am still interested in an answer to the original problem if anyone has one, but for now, what I found I could do was to create a class in .NET that I could assign to the ScriptingObject of the browser control and then call window.external.myFunctionName, where myFunctionName is a function within the .NET class. This works great for my specific problem, but would not work if I didn't also control the HTML page I was consuming with the browser. That is why I am still interested in alternate solutions if anyone has one. Thanks.
Related
I am currently trying to write a script using javascript along side a bit of html and some css - but let's stick with Javascript as thats where, I think, my problem comes from...
In short what I want my program to do is these following points:
I have an iFrame in the main window of my program.
The iFrame is used to access a website (obviously duh :P)
There is a button outside of the iFrame.
That button will call a function when pressed by the user.
HERE'S MY PROBLEM:
I want that function to simulate the press of a keyboard key (in that case, a number key followed by the ENTER key twice.
The thing is, I need to 'simulate' these keypress inside the iFrame, so they interact with the website that is access through the iFrame.
In short, I can't seem to find a way to interact with the website in iFrame from outside of it. I would prefer a solution using pure JS but I'm fully aware that there would probably be a much simpler solution using Jquery. So I'm open to either one of them.
I don't think that pieces of my code would help as there is basically nothing coded so far, besides the main function and the basic layout of the page. I'm ready to redo the whole architecture of what I've done so far if needed.
Thanks for you help.
Yann
I am working on a HTML5 application framework, run by a SAP JEE application server, build for companies and their intranet and extranet sites. It is based on the grid framework "Semantic UI" and besides that contains a lot of (also third party) Javascript.
I am currently examining a bug, where clicking a specific icon in a menu, when the page is scrolled down, makes the page somehow scroll back again upwards.
Since there is this great amount of Javascript around, I am currently struggling to find the JS code snippet, which is causing this odd behaviour.
I've read this post here, and got to know event logging in Firebug and inspecting event handlers in Chrome, but that didn't really help me.
I found out that using:
$(<my Elem>).on('click', function(event){
event.preventDefault();
})
I can prevent the scrolling, but I still didn't discover the cause of it.
Has anybody some more advice on how to find the real cause of this?
This behaviour might be caused by several different reasons. One of them that is often overlooked is links like Some JavaScript Handler.
When the JavaScript handler does not properly handle the event (e.g. by calling event.preventDefault(), the HTML link will be followed in addition to the JavaScript handler. Most browsers handle a link to an empty anchor tag # by going to the top of the page. This can easily be avoided when using an empty href attribute like <a href>Some JavaScript Handler</a>.
Imagine that there's a button on one web page (not mine) and when it's clicked it performs some
Javascript. I want to have a button on my web page that performs exactly the same. So I need to
attach all necessary js files (but first I have to find them) to my html page and sometimes add some js to my html page.
What I usually do in this case? I inspect this button html element to see if there's onclick attribute for this button. If it is, I see the function called when button is clicked and then I try to search for this function in current html page and all js files attached to page. Also I need to find all dependencies (like jQuery, fancybox etc.).
If the button doesn't have onclick attribute I have to look for direct getElementById or jQuery selector pointing to this button with rest of code there. Sometimes there's no such a selector and I have to find a nested selector - really hard and annoying thing.
Is there any better, automated way for doing things above. Ideally after selecting the element in DOM (button in this case) and pressing some magic button I will be able to see all js files involved in processing this click and also js code in html page.
It's going to involve digging no matter what you do. But Chrome's Dev Tools can help with the attached event handlers, to an extent. When you right-click an element and inspect it, on the right-hand side there's a panel showing various tabs: [Styles] [Computed] [Event Listeners] [DOM Breakpoints] [Properties]. The [Event Listeners] one shows the listeners directly attached to that element. Of course, on a site using jQuery (which is more than half the sites using JavaScript at all), looking at the handler will dump you into the jQuery event handling code, but it's a start.
Just as a side point: While it's fine to look at the source of pages for inspiration, or to see how they solved a particular problem, or what plugins they're using to get an effect, etc., I assume you're not grabbing large sections of their actual code (as opposed to libraries and plugins with liberal licenses) without their permission, which is probably not cool.
I was wondering if there is any way to find all the scripts associated with a particular element in web page.
That is if there is a photo, and there is two attached jquery function like on mouse over and on click, I need to get details of this functions without looking onto entire script.
One way is with a bookmarklet called Visual Event
There isn't really an easy way. I spent a few days trying to write an augmentation wrapper/extension that would track all even assignment in page and thus allow for inspection of such - the problem is that it requires tweaking for each library, and iirc wasn't useful if any native event assignment was used.
This is exactly the reason there needs to be well organized code, and remembering that "unobtrusive" doesn't mean "incomprehensible" - try to keep all your event assignments well organized and easily associated/found for a particular element.
My coworker and I have encountered a nasty situation where we have to use an active X control to manipulate a web camera on a page.
Is it possible to assign a javascript event handler to a button in the active x control so that it would fire an action on the page when clicked, or do we have to create a button on the html page itself that manipulates the Active X Control and then can fire any necessary actions on the page?
Please just use an existing ActiveX control. Like Flash or Silverlight. Flash has built-in webcam support and is controllable via JavaScript. Silverlight doesn't have built-in camera support, but it's JavaScript integration is fantastic.
If you must write your own then fret not, it is trivial to get it to interact with JavaScript. You just have to expose the IDispatch interface.
For events, you need to learn about Connection Points.
Yes! You can throw events in C++/ActiveX land which makes the JavaScript code run an event handler function. I was even able to make an entire invisible ActiveX control (same color as page background) with no buttons or visual feedback that did all of its GUI work through JavaScript and CSS.
edit: Frank's advice is right on. Here's the link on scripting events.
My strategy was to call a C++ function called MyUpdate (which implements IConnectionPoint) when I wanted to force updates in the browser.
(Also, I made sure to pump Windows messages in the Fire_MyUpdate method because sometimes JavaScript code would call back into C++ land by calling methods on the ActiveX control; this avoids freezing up the browser and ensures that the JavaScript GUI stays responsive, e.g. for a Cancel button.)
On the browser side, the JavaScript code has the global variable referencing the object, followed by "::", followed by the method name:
function Uploader::MyUpdate()
{
// ... code to fetch the current state of various
// properties from the Uploader object and do something with it
// for example check Uploader.IsActive and show or hide an HTML div
}