I am working with the History API and using push and pop state. I want to stop the popstate event from firing in some scenario where I am only appending the hash to URL. for example in some cases on click of anchor it appends # to the URL and popstate is immediately fired) I want to avoid all the scenarios where # or #somehasvalue is appended to the URL and stop popstate from firing. I am mainitaing the URL's with query parameters and I do not have any scenario where I need the popstate event to fire with # in the URL.
Here is my code.
if (supportsHistoryApi()) {
window.onpopstate = function (event) {
var d = event.state || {state_param1: param1, state_param2: param2};
var pathName = window.location.pathname,
params = window.location.search;
loadData(event, pathName + params, d.state_param1, d.state_param2);
}
As far as I found you cannot stop the popstate from firing unfortunately.
What you can do is check for the event.state object. That will be null on a hash change.
So I'd suggest adding a
if(event.state === null) {
event.preventDefault();
return false;
}
To your popstate event handler at the very beginning.
I think that's the best way to prevent firing of the popstate handling code on your side when the hash changes, but i'd be interested to know if there are other solutions.
I have a solution!
When popstate event calls, check the pathname if it has changed, or just the hash changed. Watch below how it works for me:
window.pop_old = document.location.pathname;
window.pop_new = '';
window.onpopstate = function (event) {
window.pop_new = document.location.pathname;
if(pop_new != pop_old){
//diferent path: not just the hash has changed
} else {
//same path: just diferent hash
}
window.pop_old = pop_new; //save for the next interaction
};
In case someone still need this:
var is_hashed = false;
$(window).on('hashchange', function() {
is_hashed = true;
});
window.addEventListener('popstate', function(e){
// if hashchange
if (is_hashed) {
e.preventDefault();
// reset
is_hashed = false;
return false;
}
// Your code to handle popstate here
..................
});
This is pretty simple.
To prevent the popstate event to fire after you click a link with hash you have to eliminate the concequence of clicking the link - which is the addition of the hash to the browser address bar.
Basically you have to create the handler for click event, check if the click is on the element you whant to prevent a hash to appear in the URL and prevent hash to appear by calling event.preventDefault(); in the handler.
Here is the code example:
/**
* This your existing `onpopstate` handler.
*/
window.onpopstate = function(e) {
// You could want to prevent defaut behaviour for `popstate` event too.
// e.preventDefault();
// Your logic here to do things.
// The following reload is just an example of what you could want to make
// in this event handler.
window.location.reload();
};
/**
* This is the `click` event handler that conditionally prevents the default
* click behaviour.
*/
document.addEventListener('click', function(e) {
// Here you check if the clicked element is that special link of yours.
if (e.target.tagName === "A" && e.target.hash.indexOf('#the-link-i-want-make-discernable') > -1) {
// The 'e.preventDefault()' is what prevent the hash to be added to
// the URL and therefore prevents your 'popstate' handler to fire.
e.preventDefault();
processMySpecialLink(e, e.target);
}
});
/**
* Just an example of the link click processor in case you want making something
* more on the link click (e.g. smooth scroll to the hash).
*/
function processMySpecialLink(e, target) {
// Make things here you want at user clicking your discernable link.
}
Here is the matching HTML markup:
<!-- Somewhere in the markup -->
<span id="the-link-i-want-make-discernable"></span>
<!-- Some markup -->
My Special Link
<!-- Another markup -->
Any other link
This all does what is described above: prevents the default behaviour for a special hash link. As a side effect it makes no popstate event to fire as no hash is added to URL for the special case of clicking the #the-link-i-want-make-discernable hash link.
I had the same problem in SPA.
I fixed this by checking if current URL and new URL are the same - technically I don't prevent popstate but I prevent fetch if hash only changed.
So, I get current URL when page loaded. It must be var to be global:
var currentURL = window.location.origin + window.location.pathname + window.location.search;
Then when history change event fired (click by link, click native browser buttons 'back' 'forward') I check if current URL and new URL are the same (hash ignored).
If URLs are the same I make return, otherwise I update current URL.
let newURL = window.location.origin + window.location.pathname + window.location.search;
if ( currentURL == newURL ) return;
currentURL = newURL;
Additionally you can to see controller code. I added it to be able stop loading when user click fast a few times 'back' or 'forward' so a few requests starter - but I need to load last one only.
Full solution of load html file when URL changed (ignore when hash only changed), with push to history, and workable 'back' and 'forward' buttons.
// get current URL when page loaded.
var currentURL = window.location.origin + window.location.pathname + window.location.search;
// function which load html.
window.xhrRequestDoc = ( currentLink, pushToHistory = true, scrollTo = 'body' ) => {
if ( pushToHistory ) {
history.pushState( null, null, currentLink );
}
// get new URL
let newURL = window.location.origin + window.location.pathname + window.location.search;
// return if hash only changed
if ( currentURL == newURL ) return;
// update URL
currentURL = newURL;
document.body.classList.add( 'main_loading', 'xhr_in_progress' );
// create controler to stop loading - used when user clicked a few times 'back' or 'forward'.
controller = new AbortController();
const signal = controller.signal;
fetch( currentLink, { signal: signal })
.then( response => response.text() )
.then( function( html ) {
// initialize the DOM parser and parse as html
let parser = new DOMParser();
let doc = parser.parseFromString( html, "text/html" );
// insert data and classes to 'body'
document.body.innerHTML = doc.querySelector( 'body' ).innerHTML;
} );
}
window.addEventListener( 'popstate', () => {
// if user clicked a few times 'back' or 'forward' - process last only
if ( document.querySelector( '.xhr_in_progress' ) ) controller.abort();
// run xhr
xhrRequestDoc( location.href, false );
})
I have an application which uses backbone hash routing. When the page reloads I use the onbeforeunload event to tell the user that there are unsaved changes and prevent the page load. This does not work on hash change; so if the user presses back the dialog does not tell them there are changes pending and just goes back.
Is there anyway to detect the hash change and prevent it happening? something like onbeforehashchange
Nope, you can detect the hashchange as it happens with something like below, but you can't really detect it before it happens. If you need the hash before it changes you can just store it somewhere.
var myHash = document.location.hash;
$(document).on('hashchange', function() {
if (myHash != document.location.hash) {
//do something
}
});
You can't really detect the back button either, and if it does'nt trigger a reload, onbeforeunload won't work either.
If this functionality is essential, you should consider trying the haschange plugin or the history plugin, as one of those would make this a lot easier, and let you control the browser history and back/forth.
I ended up creating a function in my router. This is run before each route and puts up a jquery ui dialog and waits for a reply to run the route. This is quite messy code a I stripped out the application specific stuff.
close: function(callback) {
var hash = window.location.hash;
if (this.afterHash && this.afterHash == hash) {
this.dialog.dialog("close");
return;
}
callback = callback || function () {};
if (window.onbeforeunload) {
var text = window.onbeforeunload();
if (text) {
if (!this.dialog) {
var t = this;
this.afterHash = this.previous;
this.dialog = $("<div><p>" + text + "</p><p>Are you sure you want to close the dialog?</p></div>").dialog({
modal: true,
width: 420,
title: "Confirm Navigation",
close: function() {
t.dialog.dialog("destroy");
if (t.afterHash) {
t.navigate(t.afterHash, {
trigger: false
});
t.afterHash = null;
}
t.dialog = null;
},
buttons: {
'Leave this Page': function() {
t.afterHash = null;
t.dialog.dialog("close");
closeViewer();
callback.apply(t);
},
'Stay on this Page': function() {
t.dialog.dialog("close");
}
}
});
}
return;
}
}
this.previous = window.location.hash;
callback.apply(this);
},
on initialize you must add this.previous = window.location.hash;
How can I check if a URL has changed in JavaScript? For example, websites like GitHub, which use AJAX, will append page information after a # symbol to create a unique URL without reloading the page. What is the best way to detect if this URL changes?
Is the onload event called again?
Is there an event handler for the URL?
Or must the URL be checked every second to detect a change?
I wanted to be able to add locationchange event listeners. After the modification below, we'll be able to do it, like this
window.addEventListener('locationchange', function () {
console.log('location changed!');
});
In contrast, window.addEventListener('hashchange',() => {}) would only fire if the part after a hashtag in a url changes, and window.addEventListener('popstate',() => {}) doesn't always work.
This modification, similar to Christian's answer, modifies the history object to add some functionality.
By default, before these modifications, there's a popstate event, but there are no events for pushstate, and replacestate.
This modifies these three functions so that all fire a custom locationchange event for you to use, and also pushstate and replacestate events if you want to use those.
These are the modifications:
(() => {
let oldPushState = history.pushState;
history.pushState = function pushState() {
let ret = oldPushState.apply(this, arguments);
window.dispatchEvent(new Event('pushstate'));
window.dispatchEvent(new Event('locationchange'));
return ret;
};
let oldReplaceState = history.replaceState;
history.replaceState = function replaceState() {
let ret = oldReplaceState.apply(this, arguments);
window.dispatchEvent(new Event('replacestate'));
window.dispatchEvent(new Event('locationchange'));
return ret;
};
window.addEventListener('popstate', () => {
window.dispatchEvent(new Event('locationchange'));
});
})();
Note, we're creating a closure, to save the old function as part of the new one, so that it gets called whenever the new one is called.
In modern browsers (IE8+, FF3.6+, Chrome), you can just listen to the hashchange event on window.
In some old browsers, you need a timer that continually checks location.hash. If you're using jQuery, there is a plugin that does exactly that.
Example
Below I undo any URL change, to keep just the scrolling:
<script type="text/javascript">
if (window.history) {
var myOldUrl = window.location.href;
window.addEventListener('hashchange', function(){
window.history.pushState({}, null, myOldUrl);
});
}
</script>
Note that above used history-API is available in Chrome, Safari, Firefox 4+, and Internet Explorer 10pp4+
window.onhashchange = function() {
//code
}
window.onpopstate = function() {
//code
}
or
window.addEventListener('hashchange', function() {
//code
});
window.addEventListener('popstate', function() {
//code
});
with jQuery
$(window).bind('hashchange', function() {
//code
});
$(window).bind('popstate', function() {
//code
});
EDIT after a bit of researching:
It somehow seems that I have been fooled by the documentation present on Mozilla docs. The popstate event (and its callback function onpopstate) are not triggered whenever the pushState() or replaceState() are called in code. Therefore the original answer does not apply in all cases.
However there is a way to circumvent this by monkey-patching the functions according to #alpha123:
var pushState = history.pushState;
history.pushState = function () {
pushState.apply(history, arguments);
fireEvents('pushState', arguments); // Some event-handling function
};
Original answer
Given that the title of this question is "How to detect URL change" the answer, when you want to know when the full path changes (and not just the hash anchor), is that you can listen for the popstate event:
window.onpopstate = function(event) {
console.log("location: " + document.location + ", state: " + JSON.stringify(event.state));
};
Reference for popstate in Mozilla Docs
Currently (Jan 2017) there is support for popstate from 92% of browsers worldwide.
With jquery (and a plug-in) you can do
$(window).bind('hashchange', function() {
/* things */
});
http://benalman.com/projects/jquery-hashchange-plugin/
Otherwise yes, you would have to use setInterval and check for a change in the hash event (window.location.hash)
Update! A simple draft
function hashHandler(){
this.oldHash = window.location.hash;
this.Check;
var that = this;
var detect = function(){
if(that.oldHash!=window.location.hash){
alert("HASH CHANGED - new has" + window.location.hash);
that.oldHash = window.location.hash;
}
};
this.Check = setInterval(function(){ detect() }, 100);
}
var hashDetection = new hashHandler();
Add a hash change event listener!
window.addEventListener('hashchange', function(e){console.log('hash changed')});
Or, to listen to all URL changes:
window.addEventListener('popstate', function(e){console.log('url changed')});
This is better than something like the code below because only one thing can exist in window.onhashchange and you'll possibly be overwriting someone else's code.
// Bad code example
window.onhashchange = function() {
// Code that overwrites whatever was previously in window.onhashchange
}
this solution worked for me:
function checkURLchange(){
if(window.location.href != oldURL){
alert("url changed!");
oldURL = window.location.href;
}
}
var oldURL = window.location.href;
setInterval(checkURLchange, 1000);
None of these seem to work when a link is clicked that which redirects you to a different page on the same domain. Hence, I made my own solution:
let pathname = location.pathname;
window.addEventListener("click", function() {
if (location.pathname != pathname) {
pathname = location.pathname;
// code
}
});
Edit: You can also check for the popstate event (if a user goes back a page)
window.addEventListener("popstate", function() {
// code
});
Best wishes,
Calculus
If none of the window events are working for you (as they aren't in my case), you can also use a MutationObserver that looks at the root element (non-recursively).
// capture the location at page load
let currentLocation = document.location.href;
const observer = new MutationObserver((mutationList) => {
if (currentLocation !== document.location.href) {
// location changed!
currentLocation = document.location.href;
// (do your event logic here)
}
});
observer.observe(
document.getElementById('root'),
{
childList: true,
// important for performance
subtree: false
});
This may not always be feasible, but typically, if the URL changes, the root element's contents change as well.
I have not profiled, but theoretically this has less overhead than a timer because the Observer pattern is typically implemented so that it just loops through the subscriptions when a change occurs. We only added one subscription here. The timer on the other hand would have to check very frequently in order to ensure that the event was triggered immediately after URL change.
Also, this has a good chance of being more reliable than a timer since it eliminates timing issues.
Although an old question, the Location-bar project is very useful.
var LocationBar = require("location-bar");
var locationBar = new LocationBar();
// listen to all changes to the location bar
locationBar.onChange(function (path) {
console.log("the current url is", path);
});
// listen to a specific change to location bar
// e.g. Backbone builds on top of this method to implement
// it's simple parametrized Backbone.Router
locationBar.route(/some\-regex/, function () {
// only called when the current url matches the regex
});
locationBar.start({
pushState: true
});
// update the address bar and add a new entry in browsers history
locationBar.update("/some/url?param=123");
// update the address bar but don't add the entry in history
locationBar.update("/some/url", {replace: true});
// update the address bar and call the `change` callback
locationBar.update("/some/url", {trigger: true});
To listen to url changes, see below:
window.onpopstate = function(event) {
console.log("location: " + document.location + ", state: " + JSON.stringify(event.state));
};
Use this style if you intend to stop/remove listener after some certain condition.
window.addEventListener('popstate', function(e) {
console.log('url changed')
});
The answer below comes from here(with old javascript syntax(no arrow function, support IE 10+)):
https://stackoverflow.com/a/52809105/9168962
(function() {
if (typeof window.CustomEvent === "function") return false; // If not IE
function CustomEvent(event, params) {
params = params || {bubbles: false, cancelable: false, detail: null};
var evt = document.createEvent("CustomEvent");
evt.initCustomEvent(event, params.bubbles, params.cancelable, params.detail);
return evt;
}
window.CustomEvent = CustomEvent;
})();
(function() {
history.pushState = function (f) {
return function pushState() {
var ret = f.apply(this, arguments);
window.dispatchEvent(new CustomEvent("pushState"));
window.dispatchEvent(new CustomEvent("locationchange"));
return ret;
};
}(history.pushState);
history.replaceState = function (f) {
return function replaceState() {
var ret = f.apply(this, arguments);
window.dispatchEvent(new CustomEvent("replaceState"));
window.dispatchEvent(new CustomEvent("locationchange"));
return ret;
};
}(history.replaceState);
window.addEventListener("popstate", function() {
window.dispatchEvent(new CustomEvent("locationchange"));
});
})();
While doing a little chrome extension, I faced the same problem with an additionnal problem : Sometimes, the page change but not the URL.
For instance, just go to the Facebook Homepage, and click on the 'Home' button. You will reload the page but the URL won't change (one-page app style).
99% of the time, we are developping websites so we can get those events from Frameworks like Angular, React, Vue etc..
BUT, in my case of a Chrome extension (in Vanilla JS), I had to listen to an event that will trigger for each "page change", which can generally be caught by URL changed, but sometimes it doesn't.
My homemade solution was the following :
listen(window.history.length);
var oldLength = -1;
function listen(currentLength) {
if (currentLength != oldLength) {
// Do your stuff here
}
oldLength = window.history.length;
setTimeout(function () {
listen(window.history.length);
}, 1000);
}
So basically the leoneckert solution, applied to window history, which will change when a page changes in a single page app.
Not rocket science, but cleanest solution I found, considering we are only checking an integer equality here, and not bigger objects or the whole DOM.
Found a working answer in a separate thread:
There's no one event that will always work, and monkey patching the pushState event is pretty hit or miss for most major SPAs.
So smart polling is what's worked best for me. You can add as many event types as you like, but these seem to be doing a really good job for me.
Written for TS, but easily modifiable:
const locationChangeEventType = "MY_APP-location-change";
// called on creation and every url change
export function observeUrlChanges(cb: (loc: Location) => any) {
assertLocationChangeObserver();
window.addEventListener(locationChangeEventType, () => cb(window.location));
cb(window.location);
}
function assertLocationChangeObserver() {
const state = window as any as { MY_APP_locationWatchSetup: any };
if (state.MY_APP_locationWatchSetup) { return; }
state.MY_APP_locationWatchSetup = true;
let lastHref = location.href;
["popstate", "click", "keydown", "keyup", "touchstart", "touchend"].forEach((eventType) => {
window.addEventListener(eventType, () => {
requestAnimationFrame(() => {
const currentHref = location.href;
if (currentHref !== lastHref) {
lastHref = currentHref;
window.dispatchEvent(new Event(locationChangeEventType));
}
})
})
});
}
Usage
observeUrlChanges((loc) => {
console.log(loc.href)
})
I created this event that is very similar to the hashchange event
// onurlchange-event.js v1.0.1
(() => {
const hasNativeEvent = Object.keys(window).includes('onurlchange')
if (!hasNativeEvent) {
let oldURL = location.href
setInterval(() => {
const newURL = location.href
if (oldURL === newURL) {
return
}
const urlChangeEvent = new CustomEvent('urlchange', {
detail: {
oldURL,
newURL
}
})
oldURL = newURL
dispatchEvent(urlChangeEvent)
}, 25)
addEventListener('urlchange', event => {
if (typeof(onurlchange) === 'function') {
onurlchange(event)
}
})
}
})()
Example of use:
window.onurlchange = event => {
console.log(event)
console.log(event.detail.oldURL)
console.log(event.detail.newURL)
}
addEventListener('urlchange', event => {
console.log(event)
console.log(event.detail.oldURL)
console.log(event.detail.newURL)
})
for Chrome 102+ (2022-05-24)
navigation.addEventListener("navigate", e => {
console.log(`navigate ->`,e.destination.url)
});
API references WICG/navigation-api
Look at the jQuery unload function. It handles all the things.
https://api.jquery.com/unload/
The unload event is sent to the window element when the user navigates away from the page. This could mean one of many things. The user could have clicked on a link to leave the page, or typed in a new URL in the address bar. The forward and back buttons will trigger the event. Closing the browser window will cause the event to be triggered. Even a page reload will first create an unload event.
$(window).unload(
function(event) {
alert("navigating");
}
);
window.addEventListener("beforeunload", function (e) {
// do something
}, false);
You are starting a new setInterval at each call, without cancelling the previous one - probably you only meant to have a setTimeout
Enjoy!
var previousUrl = '';
var observer = new MutationObserver(function(mutations) {
if (location.href !== previousUrl) {
previousUrl = location.href;
console.log(`URL changed to ${location.href}`);
}
});
Another simple way you can do this is by adding a click event, through a class name to the anchor tags on the page to detect when it has been clicked, then you can now use the window.location.href to get the url data which you can use to run your ajax request to the server. Simple and Easy.