I'm looking at a web page where when I push the submit button on a form, it brings up a new page where it runs some javascript and then closes the window.
Is there any way I can step through the javascript on the new page? I tried setting break on next in Firebug on the first page, but the next page still closes the window.
(I'm open to other tools besides Firebug if neccessary, I just need to step through the javascript)
Update:
I should have mentioned I don't have access to the code :-(
If you have access to the code, you can place this little statement where you want to have a breakpoint:
debugger;
I am not sure about firebug, but I expect it to work there too.
put debugger; in your JavaScript code. and press F12 key just after window open.
Related
I have a problem when I am trying to check the source of an interesting page which keeps refreshing automatically every 3-5 seconds (presumably due to some js script) which resets my Inspect Element Inspector window every time the page is refreshed.
Is there any other way other to stop that page from refreshing or perhaps the Inspector window from resetting itself other than turning on NoScript to stop the page from refreshing automatically?
Usually I just open DevTools, switch to the appropriate panel if necessary, and hit pause.
Opening DevTools: Via menus, or by press F12, Ctrl+Shift+I, or Cmd+Shift+I depending on browser and OS.
Switching panels: Pick the panel from the tabs at the top of DevTools. It'll be called "Debugger" (Firefox, IE) or "Sources" (Chrome) or similar.
Pausing: In the Debugger/Sources panel, click the pause button (usually looks like the pause button on a television remote control, ||) or press the keyboard equivalent. Keyboard equivalents are
Firefox & Chrome: F8
IE: Ctrl+Shift+B
(Updated 2020-03-30)
In Firefox 74 this option is in Options -> Privacy & Security -> Permissions
(Original reply)
Firefox has the option to prevent refresh natively, the option is in Advanced->General->Warn me when websites try to redirect or reload the page
The most popular solution for this problem is to trap the beforeunload event. The browser will ask the user for confirmation to leave the page. The code, in its simplest form, looks like this:
window.onbeforeunload = function() { return true }
You can enter this code in console. Alternately, you can simply paste the following URL in the browser address bar (console not required). You can even bookmark it.
javascript:window.onbeforeunload = function() { return true }
Be advised that modern browsers might chop off the javascript: part when you paste it inside the address bar; make sure you type it back.
To determine the cause of redirect in Firefox, try the following:
Open Web Developer Tools (CTRL + SHIFT + I), open "Toolbox Options" and check the "Enable persistent logs" option. This makes the logs persist across page loads (logs are cleared otherwise).
Now switch to "Network Monitor" tab.
Open the URL and let it refresh.
Inside the Network Monitor > Cause column you will find out why the page reloads.
The cause column is pretty ambiguous (Chrome does a much better job). However, if JavaScript was used to trigger page (re)load then it at least shows you the filename and line number of that script.
When the page is still loading, you can press the Esc key. While the page is still white, press it. When you stop the page from loading at this point, this usually stops all the auto loaded javascript. Any scripts that run on actions are usually not effected. Each page is different, try different timings.
When I use a site called NovelUpdates there is javascript that can make certain elements hidden, and when I press Esc on page load all the elements that would be hidden after page load are visible. Then when I click a button that would execute javascript that operates with no problems. NoScript isn't going to solve your issue I believe.
Another example of this are those websites with annoying boxes that pop out after 10 seconds that says you aren't a member and can't view any more of this site without logging in, like some news article websites.
What you could do is use the command exit(), which is the equivalent to die in php and simply stops the script.
If you don't know what's causing it and you don't want to look for the "bad boy", then you might as well stop the entire script at the very bottom of the page.
I have some JavaScript that, I believe, is stuck in an infinite loop. I know I can just reload the page, but I have data in a form on the current page that I'd like to keep. The tab is completely unresponsive, so I can't just copy and paste everything and then reload. So is there any way to kill the javascript thread, but keep the DOM in Chrome?
You can open the developer console F12 and stop the script
Open chrome developer tools and go to the sources tab. On the right panel press "pause script execution".
looks like someone had the same problem
Cancel infinite loop execution in jsfiddle
Answer:
With the developer mode, go into resources and find your script and copy and paste it into a text document or a new window. If you can't find it in resources, do a search for a variable or line of code you used.
I would like to know how I can use a debugger (Firebug or IE's F12 tools) to trace step by step the code I am receiving from a webpage once I POST.
My problem is that I fill out a form, and after POSTing the form, I get a response that has some redirects and other stuff apparently happening there. I would like to know how can I simply halt execution upon POST and go step by step on the javascript code that is happening, and see exactly how the redirects are formed.
The thing is I cannot place any breakpoints because I don't have the page's response before I even POST it...
I hope I was clear enough about my issue.
Thanks in advance.
You can add a debugger; statement as the first line of your JavaScript code, which launches a debugger if one is registered.
Therefore, all you need to do is ensure Firebug is launched before the page is loaded, and the JavaScript execution should be halted to allow you to step through the program.
Another (hacky) way you could do this is to place an alert() or similar as the first line; an alert() blocks the program flow until the prompt is closed. Without closing the alert, you could place a breakpoint on the next line of executable code after the alert(), then OK the alert, and then debug away.
Assuming you have IE9 installed:
Press F12.
Click on the network tab
Click "Start capturing"
Execute your script
You will see all the responses and redirecs there.
So I'm writing a watir-webdriver script, and my app is using javascript to present a modal window that I want to interact with. When I click the element that presents the modal window, watir-webdriver just sits there until eventually it times out and i see a Timeout::Error on the console window. This is before attempting to interact with the new window at all. I'm assuming it's polling the DOM for some change and not getting it, how do I tell it to move on without waiting?
The answer ended up being, and then handling the necessary waiting manually
element.focus
element.send_keys :return
Ruby 1.9.3/ IE 9 - I had a click_no_wait error. Watir would not trigger a click on the Save button, which had to be followed by a click on a java popup 'OK' button that confirmed that the save button had saved the document correctly.
Using these two lines in place of the click_no_wait command gets the code working perfectly:
element.focus
element.send_keys :return
Thanks DVG. My code -
ie.button(:id, 'MainContent_B_Save').focus
ie.button(:id, 'MainContent_B_Save').send_keys :return
ie. javascript_dialog.button('OK').click
If this is a Alert, Confirm, or Alert type JS popup, see this answer: https://stackoverflow.com/a/8172888/409820
I have some JavaScript that makes an AJAX call and, if the call fails, opens a new windows (tab in Firefox) and displays the response from the server in that window. This is very convenient for debugging, because the error is typically from Pylons, so it's a full HTML page.
The only problem is that the new tab becomes the active tab, which would totally confuse a regular user. Is there any way to open the tab/window, but not make it active, ie. keep the current active window?
My code currently looks like this:
errorWindow = window.open("", "TCerrorWindow")
if (errorWindow)
errorWindow.document.write(xhr.responseText);
You can call errorWindow.blur(); window.focus(); after, forcing the browser to return focus to the previous window.
The effect you're trying to achieve is commonly called a pop-under window.
AFAIK this is not possible, as a security measure against pop-under windows. For debugging purposes you could
use Firebug (with a handy console, where you can output your own log messages from the code)
create a debug layer (div) on your page, where you output error messages in case an error happens