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Can I "catch" a redirect executed by a script, with javascript eventListeners?

I have an HTML page that includes only a script tag, I don't control the script and I can't change it (so I can't fire my custom event for example).
The script ends with a redirect (using window.location).
Is there a way to add a new script to the page that will listen to the page events and "catch" the redirect (actually it's better for me to catch the new loaded document)?
Something like:
window.addEventListener('redirected', function() {
// do staff
});
(I know there is no "redirected" event, it's just for the example).
It's very important to make it clear that the redirect isn't caused by an anchor click or back/forward button click, so I can't use events like click or popstate.

You might want to look at the onpagehide event or the onunload event, both of which occur when the user navigates away from the page.
However, if you wish to interfere or prevent the redirection itself, onbeforeunload is what you want.

Just take a look at :
unload function w3school or mozilla developper network
beacon function for sending a final XMLHttpRequest

What's the difference between "DOMContent event" and "load event"

In chrome's Developer tool, the blue vertical line labeled "DOMContent event fired", and the red line labed "load event fired". Does "DOMContent event fired" means the browser begin to execute the inline javascript? And "load event fired" means it fire "onload" event?

"DOMContent Event" is from webkit (which chrome relies on) and is equivelant to DOMContentLoaded msdn mdn.
The DOMContentLoaded event fires when parsing of the current page is complete; the load (onload) event fires when all files have finished loading from all resources, including ads and images. DOMContentLoaded is a great event to use to hookup UI functionality to complex web pages.
See the demo here, related question.

The DOMContentLoaded event is fired when the document has been completely loaded and parsed, without waiting for stylesheets, images, and subframes to finish loading (the load event can be used to detect a fully-loaded page).

The DOMContentLoaded event is fired when the document has been completely loaded and parsed, without waiting for stylesheets, images, and subframes to finish loading (the load event can be used to detect a fully-loaded page).
check Difference between DOMContentLoaded and Load events

DOMContentLoaded is not getting triggered while visiting few sites. Any workaround?

I am developing a Firefox extension. My extension needs to get notified when a page completes loading. To implement this I am using DOMContentLoaded event. This works fine most of the times. But while visiting few sites (like nytimes.com), this event is not getting triggered at all. I am not sure whether these sites are using some special scripts.
Is there any workaround for this? Or is there a better way to implement what I am trying to do?

DOMContentLoaded may not be what you need...
According to MDN
Fired at the page's Document object when parsing of the document is
finished. By the time this event fires, the page's DOM is ready, but
the referenced stylesheets, images, and subframes may not be done
loading; use the "load" event to detect a fully-loaded page.
https://developer.mozilla.org/en/Gecko-Specific_DOM_Events
So, it is possible that nytimes.com and others my be using frames or complex CSS and that is why you are not getting the correct trigger.
As mentioned above, the "fix" is to
use the "load" event to detect a fully-loaded page

Handle window scroll event in greasemonkey script

I need some advice. I have a web page and want to extend it's functionality with greasemonkey script and firefox.
When page has loaded I need run custom function during user's page scrolling (with mouse whell or scrollbar). I want show some div block when user scrolling down and hide it when he scrolling to the top.
But I met some problem - I couldn't assign event handler to the onscroll event. I use next part of the code:
function showFixedBlock(){ ... }
function onScrollStart(){ ... showFixedBlock(); ... }
window.onscroll = onScrollStart;
I test this piece of code on my test html page and it works, but when I copy it into greasemonkey, script doesn't work.
Should I assign onscroll event handler during page loading? As I know greasemonkey execute it's scripts when page has loaded? Is it the reason of the problem?
Is there some additional requirments to handle 'onscroll' event? How can I do that?
Thanks.

I may be wrong, but I think that this should work:
unsafeWindow.onscroll = onScrollStart;
or
window.addEventListener("scroll", onScrollStart, false);
You should really use the latter example.

jQuery events .load(), .ready(), .unload()

Just a simple question, for the jQuery event. Are the .load(), .ready() and .unload() run in order when the DOM is loaded? The answer seems yes when I see the jQuery Documentation.
<script type="text/javascript">
$(window).load(function () {
// run code
initializeCode();
});
$(document).ready(function() {
//run code that MUST be after initialize
});
$(window).unload(function() {
Cleanup();
});
</script>
However, the code inside the .ready() is execute before the initializeCode(); is execute, so I feel really strange. And now I have to place my code inside the .onload() method and just after the initializeCode(); line, which means to be inside the .ready() block.
Could someone explain me more about this, as I am new to jQuery?

NOTE: .load() & .unload() have been deprecated
$(window).load();
Will execute after the page along with all its contents are done loading. This means that all images, CSS (and content defined by CSS like custom fonts and images), scripts, etc. are all loaded. This happens event fires when your browser's "Stop" -icon becomes gray, so to speak. This is very useful to detect when the document along with all its contents are loaded.
$(document).ready();
This on the other hand will fire as soon as the web browser is capable of running your JavaScript, which happens after the parser is done with the DOM. This is useful if you want to execute JavaScript as soon as possible.
$(window).unload();
This event will be fired when you are navigating off the page. That could be Refresh/F5, pressing the previous page button, navigating to another website or closing the entire tab/window.
To sum up, ready() will be fired before load(), and unload() will be the last to be fired.

window load will wait for all resources to be loaded.
document ready waits for the document to be initialized.
unload well, waits till the document is being unloaded.
the order is: document ready, window load, ... ... ... ... window unload.
always use document ready unless you need to wait for your images to load.
shorthand for document ready:
$(function(){
// yay!
});

If both "document.ready" variants are used they will both fire, in the order of appearance
$(function(){
alert('shorthand document.ready');
});
//try changing places
$(document).ready(function(){
alert('document.ready');
});

Also, I noticed one more difference between .load and .ready. I am opening a child window and I am performing some work when child window opens. .load is called only first time when I open the window and if I don't close the window then .load will not be called again. however, .ready is called every time irrespective of close the child window or not.