Using Chrome , I need to debug the java-script handler that is executed when a specific button is clicked, without searching the java-script files.
Can I use Chrome's "inspect element" for the button to find java-script handler?
Or, is there a recommended tool?
How to achieve this?
p.s: Think of a complex app within a website, I need to debug the logic behind some buttons..
When you open the developer tools on the element tab if you select the element to debug you will see at your right a tab Event Listener. It is with the Styles tab. there you can inspect the event listener. In my opinion the best way is to add break points on the sources. You'll see.
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I am attempting to make an inspect element-like tool using JS. In most browser's inspect tools you are able to hover over elements on the page and click them to show where they are in the website's code. The only way I can think of simulating this is to add event listeners to every element on the page. I feel that this is bad for a lot of reasons. Is there any other way I can do this? If not, would adding event listeners to every element on the page be a good idea?
I am switching from debugging JS in Firefox to Chrome.
One thing that I am missing is this:
In Firefox I can see in the HTML see "[event]" that there is a custom event handler attached.
I think this preview is very handy.
In chrome I need to explicitly search for the event handler.
Is there a way to enable this feature (see event-handler in the tree) in chrome, too?
The feature you are looking for is available in google chrome dev tools
I have taken, the jobs links in stack overflow page itself, it has a click event handler, to see the event handler, select the Event Listeners tab in the right part(hilighted in Red) there is a possibility that it might be hiddent by >> , click to expand,
If the ancestor checkbox is checked please uncheck this, then you will get the clear view of for which event (e.g click) , on what element (e.g anchor tag), and on right side on which file with line number, click it to navigate there.
Hope this is what you are looking for.
it's available in chrome you can find it in developers option press
(CTRL+SHIFT+I) or F12
and then you will find tab named "Event Listener" in right hand upper corner if developer options is in full screen mode or else you'll find it it lower right corner.
And if you are unable to find that just simply find the >> symbol and click on it and select Event Listeners.
Here is the image for event listeners tab.
I think you can use getEventListners($0) api of chrome which gives the event listners of the particular selected element.
getEventListners($0) where $0 - The selected element in the DOM.
The console drawer can be added to the Elements tab by clicking on Esc key it will toggle the console drawer.Then in the console you can write getEventListners($0) as shown in the image.
As this is my first answer and don't have that much reputation as of now,it is not allowing me to directly add the image to the answer so I am really sorry for that. Please have a look at the image:
Inspecting google from my chrome browser.
When I'm in a complex website such as Facebook and write a comment and push Enter there is an event fired that starts everything. Can I somehow observe which events are fired and when (and eventually somehow trace/step them)?
So in general, I'm looking for a tool capable debugging a website in this way. Is there any way?
If you are using devtools of Google Chrome, there is an Event Listeners tab that could help. See the attached picture.
There, I have selected the "Post your answer" button of this very question and as you can see, the EventListeners tab shows that there is at least an onSubmit event listener attached.
One of the debugging tool that i am using and works well for me is firebug in mozila.
you can read about firebug Here
With fire bug you can notice everything like webpage is making how much ajax call, which script is binned with which element. even you can also easily debug the css and design elements. firebug will help you more to debug the website on browser.
Say i have an icon in a webpage and i would like to figure out what happens when i click that, how do i debug that with chrome debugger? Assuming that i have the non-minified code for the webpage.
i tried to do inspect element and attaching to event handlers which doesn help much.
<span id="__icon84" data-ui="__icon84" data-ui-icon-content="" class="UiIcon UiIconMirrorInRTL" style="font-family:'icons'"></span>
all i get is that the icon used is __icon84.
PS: i am new to JS.
Use the Event Listener Breakpoints sidebar pane in the Sources panel. Expand "Mouse" and check the "click" box. Then the debugger should break whenever you enter a "click" event handler.
This question already has answers here:
Using Chrome, how to find to which events are bound to an element
(8 answers)
Closed 8 years ago.
I am looking at the Bing Maps site. I am opening up the my places editor and clicking the polyline tool in the drawing toolbar.
I would like to discover what javascript runs when I click on tools in the drawing toolbar.
I have looked at the html and there is no onclick event declared on the element.
I have done text searches on all of the scripts referenced by the page, for the ID of the polyline tool element. This was to try to find javascript that attaches a click event to the element, but I got no matches at all.
There must be some script running when I click on a tool. How do I find out what script is executing when I click the tool divs in the toolbar?
I don't think there is anyway I can set breakpoints if I don't first know what script to set them on. Is there anyway I can trap the javascript that runs to discover what it is, either in IE F12 developer tools or in firebug?
You can have a look at the "Event Listeners" panel in Chrome, it has detailed information about each listener attached to an element.
In Chrome Developer Tools click on the timeline tab, uncheck "Loading" and "Rendering", then click the record button (filled circle). Trigger your event by clicking on the button and then stop recording by clicking the circle again. Find your event in the timeline and expand it by clicking on the arrow beside it. On the left it will tell you which function the event called.
I've used the Profiler in Chrome's debug tools for this purpose before.
Open the site in Chrome, F12 to get the debug tool open. In the tabs at the top of the tool, click Profiles.
Make sure Collect JavaScript CPU Profile is selected, and hit Start, then click on the polyline tool you're curious about, and hit Stop. The profiler should now list out all Javascript calls made while the profiler was active.
Firebug probably has something similar.
To locate a potential event handler for a particular element that has been added dynamically try performing a search in all sources of classnames and ids. Once you've found an event handler you can set a breakpoint and verify.
Google Chrome has a global search that works great.
Open up your debugger and start the profiler. Click on what ever you want. Look at what the profiler and see what was called.