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Javascript - Get URL being navigated to

Is there any way to use JavaScript's OnUnload() function to find out which URL the user is navigating away to?
For example, if my code is in page1.html, and the user clicks a link to http://example.com, is there any way for JavaScript code present in page1.html, to retrieve the URL "http://example.com" and display/store it before the page unloads?
I am able to do this if I invoke a function through my link by using its OnClick, but I cannot find a way to do this otherwise. (I can post my code for that if needed, but it does meet my business requirement)
EDIT : This looks to be impossible, since my business requirement demands that I do not make any change to the content of the page, excepting the adding in of a javascript file where this code is present.

Ignore onBeforeUnload/onUnload, you don't need that. You can do it with a simple click handler like this:
$('a').on('click', function(e)
{
e.preventDefault();
var destinationLink = $(this).attr('href');
$.post('/your/analytics/url', {link:destinationLink}, function()
{
// Success
window.location.href = destinationLink;
});
});
This will stop any link from working until it's been submitted to your analytics so it's not ideal - you need to make sure what ever is receiving the data does so as quickly as possible.

You could replace the current url of the clicked link.
That will allow you to call your server to do the check of the clicked url, and then redirect it.
The code bellow change the url of the clicked link only for a couple of microseconds
$("a").on("click",function(e){
// Save the current link
var h = this.href;
//Change the link of the current a
this.href = "http://www.example1.com/redirect.php?url="+encodeURI(h);
// replace the href with the original value on the next stack
setTimeout((function(my_link){
return function(){
my_link.href = h;
};
})(this),0);
});
my link

perform href before onClick

I've the following link:
I
And this use the following javascript:
function showGallery(){
if(window.location.hash) {
$('#gallery').fadeIn('fast');
var hash = window.location.hash.substring(1);
alert(hash);
} else {
}
}
So it only show the gallery when in the URL is a hashtag. But when i click on the link, nothing happens. When i click it twice, the gallery fade in.
So the link first make the javascript, and i doesn't work 'cause there is no hashtag in the URL and after that, it perform the href and insert the Hashtag in the URL.
How can i do that?
My Target:
When i click on a link, it open a gallery. To know which gallery i must open, i insert in the URL a Hashtag. Here i want to display the HDR album. And i also want, if my site get opend with a hashtag, it should display the gallery.!
Is there also a another, easier or cleaner way to make it?
Hope you understand what i want.

For modern browsers, you can bind your Javascript code to the onhashchange event. Links will be without Javascript:
I
And the Javascript is run whenever the hash has changed:
function locationHashChanged() {
if (location.hash === "#HDR") {
$('#gallery').fadeIn('fast');
}
}
window.onhashchange = locationHashChanged;

Have you tried a setTimeout call to delay the onclick event?
Like this:
I

You can simplify this quite considerably, it is not good practice to use the href for other things than pure navigation.
<a onClick="showGallery('HDR')">I</a>
And then:
function showGallery(name){
if(name) {
$('#gallery').fadeIn('fast');
alert(name);
} else {
}
}

If you want to run showGallery() without following the link, the correct code is this:
I
By keeping the href the user still sees the destination in the status bar and navigation still works for clients without Javascript (i.e. Google). By returning false in the event handler, you prevent the browser from following the link.
In showGallery(), you can then show the gallery and add '#HDR' to the location.hash.

You don't need to verify the window's hash, because on first click you don't have any hash in the address bar. The functionality will only apply on the second click.
What you can do is this:
gallery 1
function showGallery(galid){
var linkhash = $('#' + galid).attr('href').substring(1);
alert(linkhash);
$('#gallery' + linkhash).fadeIn('fast');
}

Force page reload with html anchors (#) - HTML & JS

Say I'm on a page called /example#myanchor1 where myanchor is an anchor in the page.
I'd like to link to /example#myanchor2, but force the page to reload while doing so.
The reason is that I run js to detect the anchor from the url at the page load.
The problem (normally expected behavior) here though, is that the browser just sends me to that specific anchor on the page without reloading the page.
How would I go about doing so? JS is OK.

I would suggest monitoring the anchor in the URL to avoid a reload, that's pretty much the point of using anchors for control-flow. But still here goes. I'd say the easiest way to force a reload using a simple anchor-link would be to use
where in place of $random insert a random number (assuming "dummy" is not interpreted server side). I'm sure there's a way to reload the page after setting the anchor, but it's probably more difficult then simply reacting to the anchor being set and do the stuff you need at that point.
Then again, if you reload the page this way, you can just put myanchor2 as a query parameter instead, and render your stuff server side.
Edit
Note that the link above will reload in all circumstances, if you only need to reload if you're not already on the page, you need to have the dummy variable be more predictable, like so
I would still recommend just monitoring the hash though.

Simple like that
#hardcore
an example

Another way to do that is to set the url, and use window.location.reload() to force the reload.
<a href="/example#myanchor2"
onclick="setTimeout(location.reload.bind(location), 1)">
</a>
Basically, the setTimeout delays the reload. As there is no return false in the onclick, the href is performed. The url is then changed by the href and only after that is the page reloaded.
No need for jQuery, and it is trivial.

My favorite solution, inspired by another answer is:
myanchor2
href link will not be followed so you can use your own preference, for example: "" or "#".
Even though I like the accepted answer I find this more elegant as it doesn't introduce a foreign parameter. And both #Qwerty's and #Stilltorik's answers were causing the hash to disappear after reload for me.

What's the point of using client-side JS if you're going to keep reloading the page all the time anyways? It might be a better idea to monitor the hash for changes even when the page is not reloading.
This page has a hash monitor library and a jQuery plugin to go with it.
If you really want to reload the page, why not use a query string (?foo) instead of a hash?

Another option that hasn't been mentioned yet is to bind event listeners (using jQuery for example) to the links that you care about (might be all of them, might not be) and get the listener to call whatever function you use.
Edit after comment
For example, you might have this code in your HTML:
example1
example2
example3
Then, you could add the following code to bind and respond to the links:
<script type="text/javascript">
$('a.myHash').click(function(e) {
e.preventDefault(); // Prevent the browser from handling the link normally, this stops the page from jumping around. Remove this line if you do want it to jump to the anchor as normal.
var linkHref = $(this).attr('href'); // Grab the URL from the link
if (linkHref.indexOf("#") != -1) { // Check that there's a # character
var hash = linkHref.substr(linkHref.indexOf("#") + 1); // Assign the hash to a variable (it will contain "myanchor1" etc
myFunctionThatDoesStuffWithTheHash(hash); // Call whatever javascript you use when the page loads and pass the hash to it
alert(hash); // Just for fun.
}
});
</script>
Note that I'm using the jQuery class selector to select the links I want to 'monitor', but you can use whatever selector you want.
Depending on how your existing code works, you may need to either modify how/what you pass to it (perhaps you will need to build a full URL including the new hash and pass that across - eg. http://www.example.com/example#myanchor1), or modify the existing code to accept what you pass to it from you new code.

Here's something like what I did (where "anc" isn't used for anything else):
And onload:
window.onload = function() {
var hash = document.location.hash.substring(1);
if (hash.length == 0) {
var anc = getURLParameter("anc");
if (anc != null) {
hash = document.location.hash = anc;
}
}
}
The getURLParameter function is from here

If you need to reload the page using the same anchor and expect the browser to return to that anchor, it won't. It will return to the user's previous scroll position.
Setting a random anchor, overwriting it and then reloading seems to fix it. Not entirely sure why.
var hash = window.location.hash;
window.location.hash = Math.random();
window.location.hash = hash;
window.location.reload();

Try this its help for me
<a onclick="location.href='link.html'">click me</a>
In your anchor tag instead of
click me

As suggested in another answer, monitoring the hash is also an option. I ended up solving it like this so it required minimal code changes. If I had asked the original question, I believe I would have loved to see this option fully explained.
The added benefit is that it allows for additional code for either of the situations (hash changed or page loaded). It also allows you to call the hash change code manually with a custom hash. I used jQuery because it makes the hash change detection a piece of cake.
Here goes!
Move all the code that fires when a hash is detected into a separate independent function:
function openHash(hash) {
// hashy code goes here
return false; // optional: prevents triggering href for onclick calls
}
Then detect your hash for both scenarios like so:
// page load
$(function () {
if(typeof location.hash != typeof undefined) {
// here you can add additional code to trigger only on page load
openHash(location.hash);
}
});
// hash change
$(window).on('hashchange', function() {
// here you can add additional code to trigger only on hash change
openHash(location.hash);
});
And you can also call the code manually now like
Magic
Hope this helps anyone!

Try this by adding simple question mark:
Going to Anchor2 with Refresh

Activate URL anchor but don't scroll to it?

I have a page with two tabs that I want to be able to switch with Javascript, but also set the anchor (e.g. page.html#tab1) in the URL for bookmarking/linking.
By default the tab contents are in two divs, one below the other, and the anchor tag will scroll to the correct one, with JS disabled.
With JS enabled, CSS classes are applied to make them act as tabs. Each tab links to each anchor, but when you click to switch tabs, the page scrolls to the tab. If I return false from the onclick function then the URL doesn't change to include the anchor.
How do I make the browser URL change to page.html#tab1 but not scroll to #tab1 ??

I've played with this for a while, because I initially didn't believe you (I use the jQuery history plugin to get similar behavior).
And I'm stumped. I don't think you can. What you could do, as a workaround, is use javascript to set the hash to something DIFFERENT from what is actually on the page. And then use javascript upon load to read the hash and populate the correct content. I do this on my site. So in that scenario, users without javascript would be scrolled, users with javascript would keep the history chain, and it only gets wacky when people without send links to people with (or vice-versa).

A quick hack:
var thehash = e.target.hash;
$(thehash).prop('id',thehash.substr(1)+'-noscroll');
window.location.hash = e.target.hash;
$(thehash+'-noscroll').prop('id',thehash.substr(1));
This changes the id of the html element before and after changing the hash of the url. Works for me, but might as well break something. This prevents the browser from scrolling on a hash change, since there is not html element with that id in between.

Could you have some Javascript that changed the anchor names, set window.location.hash, and then changed the anchor names back?
(I've confirmed that andynormancx is right, and setting window.location.hash scrolls the view, but I'm too lazy to test if creating an anchor in the DOM to window.location.hash also scrolls.)

var Namespace = {
var timer, scroll;
}
// Onclick
Namespace.scroll = window.pageYOffset || document.body.scrollTop || document.documentElement.scrollTop;
Namespace.timer = setInterval(function() { scrollTo(0, Namespace.scroll) }, 100);
location.hash = this.href;
clearInterval(Namespace.timer);

I found a nice solution here: http://lea.verou.me/2011/05/change-url-hash-without-page-jump/
Use a preventDefault on for example a click event
$('a').click((event) => {
event.preventDefault();
let hash = $(event.target).attr('href');
history.pushState(null, null, hash);
// The url now has a hash but the page won't jump to the given anchor
// .. handle the rest (an easing scroll for example)
});

window.location.hash = 'tab1';
might work.

Javascript : Change the function of the browser's back button

Is there a way to make the user's back button on their browser, call a javascript function instead of going back a page?

You can't override the behaviour that if a user follows a link to your page, clicking Back will take them off it again.
But you can make JavaScript actions on your page add entries into the history as though they were clicks to new pages, and control what happens with Back and Forward in the context of those clicks.
There are JavaScript libraries to help with this, with Really Simple History being a popular example.

yes, you can. Use this js:
(function(window, location) {
history.replaceState(null, document.title, location.pathname+"#!/stealingyourhistory");
history.pushState(null, document.title, location.pathname);
window.addEventListener("popstate", function() {
if(location.hash === "#!/stealingyourhistory") {
history.replaceState(null, document.title, location.pathname);
setTimeout(function(){
location.replace("http://www.programadoresweb.net/");
},0);
}
}, false);
}(window, location));
That will redirect your back button to the location.replace you specify

I think this will do the trick.
you can write your custom code to execute on browser back button click inside onpopstate function.
This works in HTML5.
window.onpopstate = function() {
alert("clicked back button");
}; history.pushState({}, '');

I assume you wish to create a one-page application that doesn't reload the website as the user navigates, and hence you want to negate the back button's native functionality and replace it with your own. This can also be useful in mobile web-apps where using the back button inside apps is common to close an in-app window for example. To achieve this without a library, you need to:
1st. Throughout your application modify the window's location.hash instead of the location.href (which is what tags will do by default). For example, your buttons could fire on click events that modify the location.hash like this:
button.addEventListener('click', function (event) {
// Prevent default behavior on <a> tags
event.preventDefault()
// Update how the application looks like
someFunction()
// Update the page's address without causing a reload
window.location.hash = '#page2'
})
Do this with every button or tag you have that would otherwise redirect to a different page and cause a reload.
2nd. Load this code so that you can run a function every time the page history changes (both back and forward). Instead of the switch that I used in this example, you can use an if and check for other states, even states and variables not related to location.hash. You can also replace any conditional altogether and just run a function every time the history changes.
window.onpopstate = function() {
switch(location.hash) {
case '#home':
backFromHome()
break
case '#login':
backFromLogin()
break
default:
defaultBackAnimation()
}
}
This will work until the user reaches the first page they opened from your website, then it will go back to new tab, or whatever website they were in before. This can't be prevented and the teams that develop browsers are patching hacks that allow this, if a user wants to exit your website by going back, they expect the browser to do that.

If you are creating a one-page web application, where your html body has different sections and you want to nevigate through back button to the previous section you were. This answer will help you.
Where your website sections are differentiated by #. Such as:
your-web-address.com/#section-name
Just follow a few steps:
Add a class and a id in every section in you html body. Here it is ".section"
<section class="section" id="section-name">...</section>
Add two CSS class in your linked css (e.g., style.css) file to your html (e.g., index.html) file such:
.section .hide {
display: none;
}
.section .active{
dislplay: block;
}
Add this JavaScript function in you linked .js (e.g., main.js) file to your html file.
window.onpopstate = function () {
if (location.hash !== "") {
const hash = location.hash;
// Deactivating existing active 'section'
document.querySelector(".section.active").classList.add("hide");
document.querySelector(".section.active").classList.remove("active");
// Activating new 'section'
document.querySelector(hash).classList.add("active");
document.querySelector(hash).classList.remove("hide");
}
}