We recently discovered that Chrome no longer supports window.showModalDialog which is problematic because our enterprise application uses this method.
There is, apparently, a short term workaround that allows you to restore showModalDialog but it involves modifying the registry which is too complicated (and risky) four our average user. Therefore I'm not a big fan of this workaround.
The long term solution is obviously to remove all calls to this obsolete method and replace them with a convenient jQuery plugin (such as VistaPrint's Skinny Modal Dialog plugin, for example. Other suggestions are welcome by the way).
The typical scenario we use the modal dialog is to ask the user for Yes/No confirmation before executing an action that cannot be undone, ask the user to agree to terms and condition before proceeding, etc. Typically the onclick event on the "Yes" or "Ok" button in the modal dialog looks like this:
window.returnValue = true;
window.close();
Similarly, the "Cancel" or "No" button looks like this:
window.returnValue = false;
window.close();
The fact that we can return a value from the dialog is very convenient because it allows the "parent" window to be notified whether the user has clicked the "Ok" or the "Cancel" button like so:
var options = "center:1;status:1;menubar:0;toolbar:0;dialogWidth:875px;dialogHeight:650px";
var termsOfServiceAccepted = window.showModalDialog(myUrl, null, options);
if (termsOfServiceAccepted) {
... proceed ...
}
The last thing I'm going to mention about the showModalDialog is that it works great even when the document displayed in the dialog is from a different domain. It's very common for us to have our javascript running from http://the-client.com but the "Terms of Service" web page is from http://the-enterprise-vendor.com
I need a temporary solution that I can deploy ASAP while we work on the long term solution. Here are my criteria:
minimal code change in existing JavaScript
the pop up window must be able to return a value to the "parent". Typically this value is a Boolean but it could be any simple type (e.g.: string, int, etc.)
solution must work even if the URL of the content is from different domain
Here's what I have so far:
1) Add the following method in my JavaScript:
function OpenDialog(url, width, height, callback)
{
var win = window.open(url, "MyDialog", width, height, "menubar=0,toolbar=0");
var timer = setInterval(function ()
{
if (win.closed)
{
clearInterval(timer);
var returnValue = win.returnValue;
callback(returnValue);
}
}, 500);
}
As you can see in this method, I try to make the pop up window look as similar to a dialog as possible by hiding the menu and the toolbar, I setup a time every 500 milliseconds to check if the window has been closed by the user and if so, get the 'returnValue' and invoke a callback.
2) replace all calls to showModalDialog with the following:
OpenDialog(myUrl, 875, 650, function (termsOfServiceAccepted)
{
if (termsOfServiceAccepted)
{
... proceed ....
}
});
The fourth parameter to the method is the callback where I check if the user has clicked the "Ok" button before allowing her to proceed.
I know it's a long question but basically it boils down to:
What do you think of the solution I propose?
In particular, do you think I'll be able to get a returnValue from a window that was opened with window.open?
Any other alternative you can suggest?
I have two ideas that could help you but the first one is tied to CORS, so you won't be able to use it from different domains at least you can access both services and configure them.
FIRST IDEA:
The first one is related to this native api. You could create on the parent window a global function like this:
window.callback = function (result) {
//Code
}
As you can see it receives a result argument which can hold the boolean value you need. The you could open the popup using the same old window.open(url) function. The popup's onlick event handler could look like this:
function() {
//Do whatever you want.
window.opener.callback(true); //or false
}
SECOND IDEA: Solves the problem
The other idea I got is to use this other native api to trigger an event on the parent window when the popup resolves (better known as cross-document messaging). So you could do this from the parent window:
window.onmessage = function (e) {
if (e.data) {
//Code for true
} else {
//Code for false
}
};
By this way you are listening to any posted message on this window, and checking if the data attached to the message is true (the user clicks ok in the popup) or false (the user clicks cancel in the popup).
In the popup you should post a message to the parent window attaching a true or a false value when corresponds:
window.opener.postMessage(true, '*'); //or false
I think that this solution perfectly fits your needs.
EDIT
I have wrote that the second solution was also tied to CORS but digging deeper
I realized that cross-document messaging isn't tied to CORS
I want using JavaScript to see if there is history or not, I mean if the back button is available on the browser or not.
Short answer: You can't.
Technically there is an accurate way, which would be checking the property:
history.previous
However, it won't work. The problem with this is that in most browsers this is considered a security violation and usually just returns undefined.
history.length
Is a property that others have suggested...
However, the length doesn't work completely because it doesn't indicate where in the history you are. Additionally, it doesn't always start at the same number. A browser not set to have a landing page, for example, starts at 0 while another browser that uses a landing page will start at 1.
Most of the time a link is added that calls:
history.back();
or
history.go(-1);
and it's just expected that if you can't go back then clicking the link does nothing.
There is another way to check - check the referrer. The first page usually will have an empty referrer...
if (document.referrer == "") {
window.close()
} else {
history.back()
}
My code let the browser go back one page, and if that fails it loads a fallback url. It also detect hashtags changes.
When the back button wasn't available, the fallback url will be loaded after 500 ms, so the browser has time enough to load the previous page. Loading the fallback url right after window.history.go(-1); would cause the browser to use the fallback url, because the js script didn't stop yet.
function historyBackWFallback(fallbackUrl) {
fallbackUrl = fallbackUrl || '/';
var prevPage = window.location.href;
window.history.go(-1);
setTimeout(function(){
if (window.location.href == prevPage) {
window.location.href = fallbackUrl;
}
}, 500);
}
Here is how i did it.
I used the 'beforeunload' event to set a boolean. Then I set a timeout to watch if the 'beforeunload' fired.
var $window = $(window),
$trigger = $('.select_your_link'),
fallback = 'your_fallback_url';
hasHistory = false;
$window.on('beforeunload', function(){
hasHistory = true;
});
$trigger.on('click', function(){
window.history.go(-1);
setTimeout(function(){
if (!hasHistory){
window.location.href = fallback;
}
}, 200);
return false;
});
Seems to work in major browsers (tested FF, Chrome, IE11 so far).
There is a snippet I use in my projects:
function back(url) {
if (history.length > 2) {
// if history is not empty, go back:
window.History.back();
} else if (url) {
// go to specified fallback url:
window.History.replaceState(null, null, url);
} else {
// go home:
window.History.replaceState(null, null, '/');
}
}
FYI: I use History.js to manage browser history.
Why to compare history.length to number 2?
Because Chrome's startpage is counted as first item in the browser's history.
There are few possibilities of history.length and user's behaviour:
User opens new empty tab in the browser and then runs a page. history.length = 2 and we want to disable back() in this case, because user will go to empty tab.
User opens the page in new tab by clicking a link somewhere before. history.length = 1 and again we want to disable back() method.
And finally, user lands at current page after reloading few pages. history.length > 2 and now back() can be enabled.
Note: I omit case when user lands at current page after clicking link from external website without target="_blank".
Note 2: document.referrer is empty when you open website by typing its address and also when website uses ajax to load subpages, so I discontinued checking this value in the first case.
this seems to do the trick:
function goBackOrClose() {
window.history.back();
window.close();
//or if you are not interested in closing the window, do something else here
//e.g.
theBrowserCantGoBack();
}
Call history.back() and then window.close(). If the browser is able to go back in history it won't be able to get to the next statement. If it's not able to go back, it'll close the window.
However, please note that if the page has been reached by typing a url, then firefox wont allow the script to close the window.
Be careful with window.history.length because it also includes entries for window.history.forward()
So you may have maybe window.history.length with more than 1 entries, but no history back entries.
This means that nothing happens if you fire window.history.back()
You can't directly check whether the back button is usable. You can look at history.length>0, but that will hold true if there are pages ahead of the current page as well. You can only be sure that the back button is unusable when history.length===0.
If that's not good enough, about all you can do is call history.back() and, if your page is still loaded afterwards, the back button is unavailable! Of course that means if the back button is available, you've just navigated away from the page. You aren't allowed to cancel the navigation in onunload, so about all you can do to stop the back actually happening is to return something from onbeforeunload, which will result in a big annoying prompt appearing. It's not worth it.
In fact it's normally a Really Bad Idea to be doing anything with the history. History navigation is for browser chrome, not web pages. Adding “go back” links typically causes more user confusion than it's worth.
history.length is useless as it does not show if user can go back in history.
Also different browsers uses initial values 0 or 1 - it depends on browser.
The working solution is to use $(window).on('beforeunload' event, but I'm not sure that it will work if page is loaded via ajax and uses pushState to change window history.
So I've used next solution:
var currentUrl = window.location.href;
window.history.back();
setTimeout(function(){
// if location was not changed in 100 ms, then there is no history back
if(currentUrl === window.location.href){
// redirect to site root
window.location.href = '/';
}
}, 100);
Building on the answer here and here. I think, the more conclusive answer is just to check if this is a new page in a new tab.
If the history of the page is more than one, then we can go back to the page previous to the current page. If not, the tab is a newly opened tab and we need to create a new tab.
Differently, to the answers linked, we are not checking for a referrer as a new tab will still have a referrer.
if(1 < history.length) {
history.back();
}
else {
window.close();
}
This work for me using react but can work in another case; when history is in the first page (you cannot go back) window.history.state will be null, so if you want to know if you can navigate back you only need:
if (window.history.state == null) {
//you cannot go back
}
Documentation:
The History.state property returns a value representing the state at
the top of the history stack. This is a way to look at the state
without having to wait for a popstate event.
I was trying to find a solution and this is the best i could get (but works great and it's the easiest solution i've found even here).
In my case, i wanted to go back on history with an back button, but if the first page the user opened was an subpage of my app, it would go back to the main page.
The solution was, as soon the app is loaded, i just did an replace on the history state:
history.replaceState( {root: true}, '', window.location.pathname + window.location.hash)
This way, i just need to check history.state.root before go back. If true, i make an history replace instead:
if(history.state && history.state.root)
history.replaceState( {root: true}, '', '/')
else
history.back()
I came up with the following approach. It utilizes the onbeforeunload event to detect whether the browser starts leaving the page or not. If it does not in a certain timespan it'll just redirect to the fallback.
var goBack = function goBack(fallback){
var useFallback = true;
window.addEventListener("beforeunload", function(){
useFallback = false;
});
window.history.back();
setTimeout(function(){
if (useFallback){ window.location.href = fallback; }
}, 100);
}
You can call this function using goBack("fallback.example.org").
There is another near perfect solution, taken from another SO answer:
if( (1 < history.length) && document.referrer ) {
history.back();
}
else {
// If you can't go back in history, you could perhaps close the window ?
window.close();
}
Someone reported that it does not work when using target="_blank" but it seems to work for me on Chrome.
the browser has back and forward button. I come up a solution on this question. but It will affect browser forward action and cause bug with some browsers.
It works like that: If the browser open a new url, that has never opened, the history.length will be grow.
so you can change hash like
location.href = '#__transfer__' + new Date().getTime()
to get a never shown url, then history.length will get the true length.
var realHistoryLength = history.length - 1
but, It not always work well, and I don't known why ,especially the when url auto jump quickly.
I am using window.history in Angular for the FAQ on my site.
Whenever the user wants to exit the FAQ they can click the exit button (next to the back button)
My logic for this "exit" strategy is based on the entry ID and then just go back the number of states till that state.
So on enter:
enterState: { navigationId:number } = {navigationId: 1}
constructor() {
this.enterState = window.history.state
}
pretent the user navigates through the faq
And then, when the user clicks the exit button, read the current state and calculate your delta:
exitFaq() {
// when user started in faq, go back to first state, replace it with home and navigate
if (this.enterState.navigationId === 1) {
window.history.go((window.history.state.navigationId - 1) * -1)
this.router.navigateByUrl('/')
// non-angular
// const obj = {Title: 'Home', Url: '/'}
// window.history.replaceState(obj, obj.Title, obj.Url)
} else {
window.history.go(this.enterState.navigationId - window.history.state.navigationId - 1)
}
}
As you can see, I also use a fallback for when the user started in the faq, in that case the state.navigationId is 1 and we want to route back, replace the first state and show the homepage (For this I'm using the Angular router, but you can use history.replaceState as well when you handle your own routes)
For reference:
history.go
history.state
history.replaceState
Angular.router.navigateByUrl
This might help:
const prev = window.location.pathname;
window.history.back();
setTimeout(() => {
if (prev === window.location.pathname) {
// Do something else ...
}
}, 1000);
I'm using Angular, I need to check if there is history, trigger location.back(), else redirect to parent route.
Solution from https://stackoverflow.com/a/69572533/18856708 works well.
constructor(
private activatedRoute: ActivatedRoute,
private router: Router,
private location: Location,
}
...
back(): void {
if (window.history.state === null) {
this.router.navigate(['../'], { relativeTo: this.activatedRoute });
return;
}
this.location.back();
}
This is my solution:
function historyBack() {
console.log('back');
window.history.back() || window.history.go(-1);
if (!window.history.length) window.close();
var currentUrl = window.location.href;
setTimeout(function(){
// if location was not changed in 100 ms, then there is no history back
if(current === window.location.href){
console.log('History back is empty!');
}
}, 100);
}
function historyForward() {
console.log('forward');
window.history.forward() || window.history.go(+1);
var current = window.location.href;
setTimeout(function(){
// if location was not changed in 100 ms, then there is no history forward
if(current === window.location.href){
console.log('History forward is empty!');
}
}, 100);
}
The following solution will navigate back AND will tell if the navigation occurred or not:
async function goBack() {
return new Promise((resolve, reject) => {
const timer = setTimeout(() => reject('nowhere to go'), 100);
window.history.back();
const onBack = () => {
window.removeEventListener('beforeunload', onBack);
window.removeEventListener('popstate', onBack);
clearTimeout(timer);
resolve(true);
};
window.addEventListener('beforeunload', onBack);
window.addEventListener('popstate', onBack);
});
}
// usage
await goBack().catch(err => console.log('failed'));
How it works:
Try to navigate back
Add event listeners that will trigger on navigation to another website or to another page on the same site (SPA website, etc.)
If above events didn't occur in 100ms, deduce that there's nowhere to go back to
Notice that goBack() is an async function.
var fallbackUrl = "home.php";
if(history.back() === undefined)
window.location.href = fallbackUrl;
I am using a bit of PHP to achieve the result. It's a bit rusty though. But it should work.
<?php
function pref(){
return (isset($_SERVER['HTTP_REFERER'])) ? true : '';
}
?>
<html>
<body>
<input type="hidden" id="_pref" value="<?=pref()?>">
<button type="button" id="myButton">GoBack</button>
<!-- Include jquery library -->
<script>
if (!$('#_pref').val()) {
$('#myButton').hide() // or $('#myButton').remove()
}
</script>
</body>
</html>
var func = function(){ console.log("do something"); };
if(document.referrer.includes(window.location.hostname) && history.length-1 <= 1){
func();
}
else{
const currentUrl = window.location.href;
history.back();
setTimeout(function(){
currentUrl === window.location.href && func();
}, 100);
}
I found a JQuery solution that actually works
window.history.length == 1
This works on Chrome, Firefox, and Edge.
You can use the following piece of JQuery code that worked for me on the latest versions of all of the above 3 browsers if you want to hide or remove a back button on your developed web page when there is no window history.
$(window).load(function() {
if (window.history.length == 1) {
$("#back-button").remove();
}
})
Solution
'use strict';
function previousPage() {
if (window.location.pathname.split('/').filter(({ length }) => length > 0).length > 0) {
window.history.back();
}
}
Explaination
window.location.pathname will give you the current URI. For instance https://domain/question/1234/i-have-a-problem will give /question/1234/i-have-a-problem. See the documentation about window.location for more informations.
Next, the call to split() will give us all fragments of that URI. so if we take our previous URI, we will have something like ["", "question", "1234", "i-have-a-problem"]. See the documentation about String.prototype.split() for more informations.
The call to filter() is here to filter out the empty string generated by the backward slash. It will basically return only the fragment URI that have a length greater than 1 (non-empty string). So we would have something like ["question", "1234", "i-have-a-question"]. This could have been writen like so:
'use strict';
window.location.pathname.split('/').filter(function(fragment) {
return fragment.length > 0;
});
See the documentation about Array.prototype.filter() and the Destructuring assignment for more informations.
Now, if the user tries to go back while being on https://domain/, we wont trigger the if-statement, and so wont trigger the window.history.back() method so the user will stay in our website. This URL will be equivalent to [] which has a length of 0, and 0 > 0 is false. Hence, silently failing. Of course, you can log something or have another action if you want.
'use strict';
function previousPage() {
if (window.location.pathname.split('/').filter(({ length }) => length > 0).length > 0) {
window.history.back();
} else {
alert('You cannot go back any further...');
}
}
Limitations
Of course, this solution wont work if the browser do not support the History API. Check the documentation to know more about it before using this solution.
I'm not sure if this works and it is completely untested, but try this:
<script type="text/javascript">
function goBack() {
history.back();
}
if (history.length > 0) { //if there is a history...
document.getElementsByTagName('button')[].onclick="goBack()"; //assign function "goBack()" to all buttons onClick
} else {
die();
}
</script>
And somewhere in HTML:
<button value="Button1"> //These buttons have no action
<button value="Button2">
EDIT:
What you can also do is to research what browsers support the back function (I think they all do) and use the standard JavaScript browser detection object found, and described thoroughly, on this page. Then you can have 2 different pages: one for the "good browsers" compatible with the back button and one for the "bad browsers" telling them to go update their browser
Check if window.history.length is equal to 0.
We recently discovered that Chrome no longer supports window.showModalDialog which is problematic because our enterprise application uses this method.
There is, apparently, a short term workaround that allows you to restore showModalDialog but it involves modifying the registry which is too complicated (and risky) four our average user. Therefore I'm not a big fan of this workaround.
The long term solution is obviously to remove all calls to this obsolete method and replace them with a convenient jQuery plugin (such as VistaPrint's Skinny Modal Dialog plugin, for example. Other suggestions are welcome by the way).
The typical scenario we use the modal dialog is to ask the user for Yes/No confirmation before executing an action that cannot be undone, ask the user to agree to terms and condition before proceeding, etc. Typically the onclick event on the "Yes" or "Ok" button in the modal dialog looks like this:
window.returnValue = true;
window.close();
Similarly, the "Cancel" or "No" button looks like this:
window.returnValue = false;
window.close();
The fact that we can return a value from the dialog is very convenient because it allows the "parent" window to be notified whether the user has clicked the "Ok" or the "Cancel" button like so:
var options = "center:1;status:1;menubar:0;toolbar:0;dialogWidth:875px;dialogHeight:650px";
var termsOfServiceAccepted = window.showModalDialog(myUrl, null, options);
if (termsOfServiceAccepted) {
... proceed ...
}
The last thing I'm going to mention about the showModalDialog is that it works great even when the document displayed in the dialog is from a different domain. It's very common for us to have our javascript running from http://the-client.com but the "Terms of Service" web page is from http://the-enterprise-vendor.com
I need a temporary solution that I can deploy ASAP while we work on the long term solution. Here are my criteria:
minimal code change in existing JavaScript
the pop up window must be able to return a value to the "parent". Typically this value is a Boolean but it could be any simple type (e.g.: string, int, etc.)
solution must work even if the URL of the content is from different domain
Here's what I have so far:
1) Add the following method in my JavaScript:
function OpenDialog(url, width, height, callback)
{
var win = window.open(url, "MyDialog", width, height, "menubar=0,toolbar=0");
var timer = setInterval(function ()
{
if (win.closed)
{
clearInterval(timer);
var returnValue = win.returnValue;
callback(returnValue);
}
}, 500);
}
As you can see in this method, I try to make the pop up window look as similar to a dialog as possible by hiding the menu and the toolbar, I setup a time every 500 milliseconds to check if the window has been closed by the user and if so, get the 'returnValue' and invoke a callback.
2) replace all calls to showModalDialog with the following:
OpenDialog(myUrl, 875, 650, function (termsOfServiceAccepted)
{
if (termsOfServiceAccepted)
{
... proceed ....
}
});
The fourth parameter to the method is the callback where I check if the user has clicked the "Ok" button before allowing her to proceed.
I know it's a long question but basically it boils down to:
What do you think of the solution I propose?
In particular, do you think I'll be able to get a returnValue from a window that was opened with window.open?
Any other alternative you can suggest?
I have two ideas that could help you but the first one is tied to CORS, so you won't be able to use it from different domains at least you can access both services and configure them.
FIRST IDEA:
The first one is related to this native api. You could create on the parent window a global function like this:
window.callback = function (result) {
//Code
}
As you can see it receives a result argument which can hold the boolean value you need. The you could open the popup using the same old window.open(url) function. The popup's onlick event handler could look like this:
function() {
//Do whatever you want.
window.opener.callback(true); //or false
}
SECOND IDEA: Solves the problem
The other idea I got is to use this other native api to trigger an event on the parent window when the popup resolves (better known as cross-document messaging). So you could do this from the parent window:
window.onmessage = function (e) {
if (e.data) {
//Code for true
} else {
//Code for false
}
};
By this way you are listening to any posted message on this window, and checking if the data attached to the message is true (the user clicks ok in the popup) or false (the user clicks cancel in the popup).
In the popup you should post a message to the parent window attaching a true or a false value when corresponds:
window.opener.postMessage(true, '*'); //or false
I think that this solution perfectly fits your needs.
EDIT
I have wrote that the second solution was also tied to CORS but digging deeper
I realized that cross-document messaging isn't tied to CORS
I’ve made a one page site. When user clicks on the menu buttons, content is loaded with ajax.
It works fine.
In order to improve SEO and to allow user to copy / past URL of different content, i use
function show_content() {
// change URL in browser bar)
window.history.pushState("", "Content", "/content.php");
// ajax
$content.load("ajax/content.php?id="+id);
}
It works fine. URL changes and the browser doesn’t reload the page
However, when user clicks on back button in browser, the url changes and the content have to be loaded.
I've done this and it works :
window.onpopstate = function(event) {
if (document.location.pathname == '/4-content.php') {
show_content_1();
}
else if (document.location.pathname == '/1-content.php') {
show_content_2();
}
else if (document.location.pathname == '/6-content.php') {
show_content_();
}
};
Do you know if there is a way to improve this code ?
What I did was passing an object literal to pushState() on page load. This way you can always go back to your first created pushState. In my case I had to push twice before I could go back. Pushing a state on page load helped me out.
HTML5 allows you to use data-attributes so for your triggers you can use those to bind HTML data.
I use a try catch because I didn't had time to find a polyfill for older browsers. You might want to check Modernizr if this is needed in your case.
PAGELOAD
try {
window.history.pushState({
url: '',
id: this.content.data("id"), // html data-id
label: this.content.data("label") // html data-label
}, "just content or your label variable", window.location.href);
} catch (e) {
console.log(e);
}
EVENT HANDLERS
An object filled with default information
var obj = {
url: settings.assetsPath, // this came from php
lang: settings.language, // this came from php
historyData: {}
};
Bind the history.pushState() trigger. In my case a delegate since I have dynamic elements on the page.
// click a trigger -> push state
this.root.on("click", ".cssSelector", function (ev) {
var path = [],
urlChunk = document.location.pathname; // to follow your example
// some data-attributes you need? like id or label
// override obj.historyData
obj.historyData.id = $(ev.currentTarget).data("id");
// create a relative path for security reasons
path.push("..", obj.lang, label, urlChunk);
path = path.join("/");
// attempt to push a state
try {
window.history.pushState(obj.historyData, label, path);
this.back.fadeIn();
this.showContent(obj.historyData.id);
} catch (e) {
console.log(e);
}
});
Bind the history.back() event to a custom button, link or something.
I used .preventDefault() since my button is a link.
// click back arrow -> history
this.back.on("click", function (ev) {
ev.preventDefault();
window.history.back();
});
When history pops back -> check for a pushed state unless it was the first attempt
$(window).on("popstate", function (ev) {
var originalState = ev.originalEvent.state || obj.historyData;
if (!originalState) {
// no history, hide the back button or something
this.back.fadeOut();
return;
} else {
// do something
this.showContent(obj.historyData.id);
}
});
Using object literals as a parameter is handy to pass your id's. Then you can use one function showContent(id).
Wherever I've used this it's nothing more than a jQuery object/function, stored inside an IIFE.
Please note I put these scripts together from my implementation combined with some ideas from your initial request. So hopefully this gives you some new ideas ;)