I've got a pretty big complicated HTML5 app I'm working on (backbone, marionette, jQuery, underscore, handlebars, bootstrap, etc) and deep within the app is a modal popup with a form in it.
When the modal pops open, the first time you click on any form field the form field de-selects itself. After that first click you can use the form as normal. When the app is ultimately loaded into an iFrame in production (don't ask) the first time you click on any form field or hover over any button, the whole page scrolls down until the top of the div element the form is within inside of the modal is at the top of the page, but after it does this once, it doesn't do it again (confused yet? Yeah, it's complex and layered).
I'm at a loss for how to even begin debugging this problem (thousands of lines of code, two handfuls of libraries).
I tried these:
console.log('bound events: ', $._data(this.$el.find('#RandomFieldID')[0], 'events'));
console.dir($('#elmId').data('events'));
console.log('bound events: ', $._data($('body')[0], 'events'));
But that yielded nothing.
Since this is library upon library upon framework upon framework I'm not even sure where to begin trying to find the thing that has obviously bound itself to these fields, or even if it is the fields that are being bound to or something else entirely...
So, any suggestions on good strategies for how to debug a mysteriously bound Javascript event (with multiple JS libraries and frameworks, which can't be just commented out until the problem resolves because they are relied upon to even get the HTML to appear on the page in the first place)?
And, unfortunately I can't do a jsfiddle or something because, as I said, this is deep deep within the app and I'd basically have to re-create the app inside of JSFiddle (impossible) to link to an example (and, it's not in an external facing site, so, I can't just link to it live in production).
I'm stumped.
Here's how I do it with Chrome.
Ctrl-Shift-J to open Javascript console.
Click the little magnifying glass in bottom left, it lets you select an element with your mouse.
Click an element on your page (it will highlight as you go to it.) It will highlight in the DOM at the bottom and show a bunch of properties on the bottom right.
At the bottom right go all the way past the CSS attributes and stuff down to event listeners:
Pick the event listener you're interested in. It will show you the bound function as well as the exact line of code in what script would be executed. That should tell you what library is doing your crazy stuff.
I find the Chrome debugger to be much more powerful and fast (doesn't lag) compared to FireBug and the IE developer tools. It's highly recommended :)
Related
I'm trying to debug the integration between my app and Stripe's Elements component library. Everything works fine in sandbox mode, but we ran into a problem on production in the 3D Secure authentication process. This involves loading an iframe, into our app, that contains a form from the credit card's issuer (usually via a technology partner, like Arcot).
The form loads correctly and its buttons are working as expected, but the element (for a SMS one time code) is not behaving. Every time I click on the input, something is immediately pushing the focus back to the element of the iframe. This makes it impossible to type anything in, since by the time I touch a key, the input is not in focus. For reference, it is possible to change the input's value using document.getElementById('enterPIN').value = '123456';
I'm not sure if my app is triggering focus() calls (I don't think so) or if it is some part of the iframe code or even Stripe's. Is there a good way to monitor DOM events and do a stack trace for the trigger of each one?
I tried two tactics. Neither gave an obvious answer, but they did point my search in the right direction.
I opened the Event Listeners panel (in the Elements tab of my browser's developer tools) and removed everything I could find, but it seems that this doesn't actually change the behavior of the page- focus kept being stolen away. Luckily, I also noticed some listeners that were defined by the Material UI library.
I used monitorEvents() to get a few more details, but the src & target values were not much help and event.relatedTarget was always null.
In the end, I found this discussion and realized that my MUI Dialog component was stealing focus whenever I clicked on the iframe triggered by its content. This was easily fixed by adding the disableEnforceFocus attribute.
Recently we implemented the GoogleTagManager (GTM), and certain Jquery UI dialogs are not showing at all (some of them always work, some of them never work, consistently). Unfortunately, I cannot provide sample codes.
When a UI button is clicked that calls .dialog("open") the dialog is not shown but the entire page goes grey (div class="ui-widget-overlay ui-front"). I see in the html that the div has "display:none" style.
If I remove the display: none, the dialog is finally shown, but the form's UI is messed up. Somehow the width of the modal is 300px instead of 1000px, etc. Also, the event listeners from the save/cancel buttons are missing. If I put autoOpen: true on the jquery UI dialog declaration, the dialog is shown, but is still messed up the same way.
I noticed that when I have an adblocker, everything works properly, but when I don't, the bug appears. I also realized that a "fbevents.js" file is in the browser when GTM is used, and if I explicitly disable only this file with an adblocker, the bug disappears.
I also see a facebook.com/tr/ call that stays "pending" forever in the network tab in Chrome, when I click on the icon that calls the dialog("open").
And of course, if there is no GTM, the site works properly.
Do you have any idea what is this bug or how should I continue the investigation? (without updating jquery/jqueryUI or without switching to bootstrap modal)?
Without additional detail is very hard to guess, what causes your problem, but there is one thing, I will try ona first place.
Check, how is your trigger made.
There are some GTM configurations, that steps into link click event processing.
So maybe, there is an event listenning on an A element, that onlky pretends to be a link and GTM is waiting for response.
If this is a true, try to change event listener into just Generic click event (Click - All Elements).
I got lucky. I found a second form that exists for a short period of time, which was facebook related (GTM). I realized that a "xy.appendTo('form')" JS code inserts data into the wrong form... By changing the code to "xy.appendTo('#form1')" the problem is gone.
So a simple appendTo('form') started the domino effect, which resulted in duplicated IDs in the DOM, and messed up everything...
The facebook.com/tr call in the network tab is still in pending state, but I believe that is somehow related to Jakub Kriz's suggestion (I will update my answer soon).
UPDATE:
Even though the GTM debugger shows no trigger has been fired, the GTM sends requests to facebook.com/tr calls every time a "a/a href" or "input type="button"" is clicked. I believe this is a default functionality, and I understand why.
In some cases our website is using these html tags in an invalid way: "a" is used instead of a "div" and "input type button" is used for an icon that opens a modal dialog. If we change these, the unnecessary facebook.com/tr calls will be gone.
But I've got still no clue about the pending state. I believe when I apply the changes I mentioned above, the problem will be gone.
So I have a very specific problem that presented itself recently (right before our planned launch day tomorrow) and I am not completely sure how to solve it. I have built our website of an HTML-template with my modest front-end skills and we are very pleased with it. However, I can't seem to solve this.
The problem:
I have a filter system that allows a user to filter articles that are presented on a page. A user can even fill in this filter on the home page, direct to the page with the articles and have the filter applied. However, if then the filter is broadened (less strict) and new articles present itself, the pictures do not show up. Found out this is the case because the flexslider behind it has to be initialized again which happens on a window load (e.g. when the window is resized). The function that controls the initialization of the flexslider is in an external js file and I am not sure whether I can call on it from my own custom.js file, so I am thinking of just calling a resize/reload window function to active it.
The question:
Can I run a resize window function (or something that activates the flexslider) without hindering user experience (more specifically, without ACTUALLY resizing/reloading the window)? I will run this on a change in the filter.
I know this is a very specific question but hopefully somebody can help me out.
Take care!
p.s. it would be ideal if I could run the actual function that loads the flexslider but this is located in an external js file.
EDIT:
Briefly some additional info. If I go straight to the article page, it has no filter active and thus shows all articles, if I then start flipping through the filter, all is good. It is however only if I arrive from the homepage with a set filter that the problems arise. You then arrive on the article page which shows only the articles that are within the boundaries, and when the filter is taken away it has problems loading the images of the new articles showing up. As if it had not loaded these because they were not open on window load the first time.
You can trigger a resize event by creating a new event and passing it into the dispatchEvent command on window. There's a nice guide here. You'll want the type of event to be resize, since that's what it's listening for.
window.dispatchEvent(new Event('resize'))
This will work for events that were added via jQuery as well as events added via addEventListener.
I managed to solve it after all by delaying the function that drops the filter values into my inputs so it loads in all images initially before applying the filter. It happens at such speed it's hardly noticeable.
Also, I did try to initiate a window resize function, it did work without actually resizing anything, but unfortunately the images did not load in properly (overlap and such).
Anyway, it has been solved. Thanks for all the input!
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.
Is there a tool (or something in firebug) that will tell me what events just fired and more importantly on what elements they were bound to?
I have a number of javascript "includes", some minified, some not. I am experiencing some odd behaviour that I want to turn off, but I cannot find what is causing it.
I have a form showing in a "popup" and when I try to click on one of the input boxes, the "popup" closes, so some event bind somewhere is causing this.
The problem is, I don't know what element has this spurious event bound to it. The problem also occurs if I click anywhere inside the popup (and on the background mask that is covering the rest of the page, but that's acceptable)
I am using firefox, so anything I can type in the console is also an option. The eventys in the multiple javascript files are done in various ways, some through jquery, some using inline attributes (eg. onclick="..."), some using just javascript.
I certainly don't want to go and add some line of code to every possible event in every javascript file.
I have spent over an hour trying to hunt down this dom element and have already eliminated the obvious ones like the divs containing the popup and the body tag.
DOM modifications can be tracked down using the Break On Mutate option within Firebug. It can be activated by clicking the related button ( ) within the HTML panel. Note that the Script panel has to be enabled for this to work.
There are also several other Break On ... features, which may help you finding the right position within the code for a specific event.
Furthermore Firebug 2.0 introduced an Events side panel, which displays all events bound to the element selected within the HTML panel. If libraries like jQuery are used, it will even allow you to investigate the user-defined function wrapped by the library function in case you enable the option Show Wrapped Listeners as described in the answer to a related question.