Javascript : make request again when accessing previous state - javascript

I use this in my JS:
window.history.replaceState({url: , scrollTop: wTop}, 'foo', 'bar');
But when I go to another page from here then press the back button, I end up not firing a request. Instead, my browser loads everything back from its "disk cache". I'd like to fire the request again, since my state has change and it should ask for the corrected page.
How can I achieve that?
I tried with this in my rails controller:
response.headers['Cache-Control'] = 'no-cache, no-store, must-revalidate'
response.headers['Pragma'] = 'no-cache'
response.headers['Expires'] = '0'
But apparently, the history list is not entirely related to the cache feature.

I'd do it with a hidden input and a bit of script. Something like the following assuming you have jQuery available (obviously just modify it if you're not using it):
<input type="hidden" id="reload_page" value="false" />
And then:
$(document).ready(function() {
if ($("#reload_page").val() == "true") {
location.reload(true);
} else {
$("#reload_page").val("true");
}
}
The "true" flag in the location.reload event tells it to reload the page from the server instead of from the cache. The browser should store your input value as part of the cache, so the page will refresh when you return to it, but not when it first loads.
If you're working with a page that has been added instead, so that it has no historical state, you can reverse the process a little -- instead of a direct reload, as in the above, add a form to submit rather than a direct reload, something like the following:
<form id="reload_form" method="get">
<input type="hidden" id="no_refresh" val="true" />
</form>
Paired with a similar bit of script:
$(document).ready(function() {
if (!$.urlParam('no_refresh')) {
$("#reload_form").submit();
}
});
This makes use of the $.urlParam function found here, but works on a similar principle to the natural "back" function in the snippet above -- once the form is submitted to refresh the page, the parameter becomes available, and the changed state prevents the script from refreshing the page.

You need to add a pop state listener.
window.onpopstate = function(event) {
alert("location: " + document.location + ", state: " + JSON.stringify(event.state));
};
If you don't add this listener, then the browser will behave in the traditional fashion, requesting the page from the server (or loading from cache) when the state changes.
NOTE: The browser caching header can still be used with push/pop state which improves first page loading.

Related

window.location not refreshing to the existing URL

I have a PHP page with implementation of jQuery horizontal tabs. I have added a jQuery script so that the page URL reflects the tab#. I have a form on the page and upon form submission I need to refresh and stay on this same page to include the jQuery correct tab number.
This is the code to add the jQuery tab number to the URL:
<script>
jQuery(function($) {
$("<p>").html("Loaded at " + new Date()).appendTo(
document.body
);
showTab(location.hash || "#tabs-1");
$("#nav a").click(function() {
var hash = this.getAttribute("href");
if (hash.substring(0, 1) === "#") {
hash = hash.substring(1);
}
location.hash = hash;
showTab(hash);
return false;
});
function showTab(hash) {
$("div.tab").hide();
$("#tab-" + hash).show();
}
});
</script>
The full URL of the page is http://somedomain.com/includes/nonadmin_user_profile.php#tabs-5 and includes the tab number for the jQuery horizontal tab.
I am using this script to refresh and stay on the same page: echo "<script>window.location=window.location</script>";
On refresh here is the problem as it lands at this URL which does not include the tab number. http://somedomain.com/includes/nonadmin_user_profile.php
Any suggestions would be appreciated very much.
Here is another detail: The problem described above does not occur if I merely refresh the page with the browser refresh button or if I right click the page and refresh. In this instance the page refreshes and stays on the full url with the tab#.
Per Disaster Faster's request, the issue encountered was simply that the browser was not going to the desired location of the page. The form data was successfully submitted and correct page was loaded.
The solution to his issue was modifying the form's action attribute to include the location information (similar to adding location information to an anchor).
Original:
<form action="nonadmin_user_profile.php" method="post">
New:
<form action="nonadmin_user_profile.php#tabs-5" method="post">
Original Post:
The window.location = window.location redirect should include the location information.
JSFiddle: http://jsfiddle.net/6dqcmh9d/
If you click the button first, it'll report the URL with the location information because it hasn't been added to the URL. Then click the link and re-click the button. You'll receive the URL with the location information added.
If you want just the location information, you can use window.location.hash, but this will only produce the location on the page, not the URL of the page.
The problem you'll run into will be with the form submission. To submit a form without changing the page, you'll either have to submit the form to a new window (add target="_blank" to the form) or implement AJAX. In either case, we'd need a little more of your code to help with integrating it properly.
It is likely that the tab controls are being handled with onclick events or something similar, and are not listening for hash changes onload. You'll likely need to add some custom JS to force the tab change if there's a hash change.
What's wrong with using the reload() method?
document.location.reload(true);
From the docs:
The Location.reload() method Reloads the resource from the current
URL. Its optional unique parameter is a Boolean, which, when it is
true, causes the page to always be reloaded from the server. If it is
false or not specified, the browser may reload the page from its
cache.
If you need to integrate it into a PHP echo struct, use:
echo '<script>document.location.reload(true);</script>';
You should use reload() to refresh the page, eg:
window.location.reload();
Or given your example:
echo "<script>window.location.reload();</script>";

How to change URL path when paging using ajax + jQuery

I am using ajax post requests for doing paging on a feed in my site. When getting the post request data I am reforming the page by clearing previous data and rendering the new data that came from the request. I want to be able to change the URL as well so saving the new page link will get the user to the current page.
Example:
User on page example.com/feed - seeing content of page #1
User clicking to get to page #2 -> ajax post is send and data on the page is changed using js (no refresh)
URL is still example.com/feed but the content is of example.com/feed?page=2
How can I set the URL to point to the new page without triggering a refresh (no redirect) ?
I am using Nodejs + express.
I understand you are aiming at a single page application.
While keeping the url is nice, note you might want distinct urls for directly accessing different parts of your application. Still, you can load content with AJAX and keep a smooth application. The way to go is using the hash part of the location.
The Sammy.js framework gives you a nice base to build upon, you can try it out.
You can use history pushstate but some browsers does not support.
history.pushState({id: 'SOME ID'}, '', 'myurl.html');
And don't forget about window.onpopstate, it pops if user clicks back button.
Redirect the user to an anchor point.
Page 2
And in your document.ready:
if (window.location.hash.length > 1){
var pageNumber = window.location.hash.substring(1);
loadPage(parseInt(pageNumber));
} else{
loadPage(0);
}
I don't believe it is possible to change the query part of the URL without triggering a refresh (probably due to security issues). However you may change the anchor and use an event listener to detect when the anchor is being changed.
//Listener
$(window).on('hashchange', function() {
if(loaction.hash.length > 1) {
//The anchor has been changed.
loadPageWithAjax("example.com/feed.php?page=" + location.hash.substring(1));
} else {
//Load standard page
...
}
});
Change the anchor to load new feed
Page 2
Remember to not use an anchor that is used as an id, since this makes the browser scroll to that element.

Detect first page load with jQuery?

I need to detect the first time a page loads in jQuery so that I can perform some actions only when the page loads the first time a user navigates to that page. Similar to server side code page.ispostbasck. I have tested $(document).ready and it fires every time the page loads so this will not provide what I need. I have also tried the jQuery Load function - it also fires every page load. So by page load an example is that I have an HTML input tag on the page of type button and it does not fire a postback (like an asp.net button) but it does reload the page and fires $(document).ready
Thanks
You will have to use cookie to store first load information:
if (! $.cookie("cookieName")){
// do your stuff
// set cookie now
$.cookie("cookieName", "firstSet", {"expires" : 7})
}
Note: Above example uses jQuery Cookie plugin.
An event doesn't exist that fires only when the page is loaded for the first time.
You should use jQuery's .ready() event, and then persist the fact that you've handled a first time page load using your method of choice (i.e. cookie, session variable, local storage, etc.).
Note: This method will never be fool proof unless you can store this information at the user level in a DB. Otherwise, as soon as the user clears their cookies, or whatever method you choose, the "first time loaded" code will fire again.
I just ran into this problem and this is how I handled it. Keep track of the first time the page loads by using a variable initialLoad:
var initialLoad = true;
$(document).ready(function() {
...
...
...
initialLoad = false;
});
Then in other functions, you can do this:
if (initialLoad) {
//Do work that is done when the page was first refreshed/loaded.
} else {
//Do work when it's not the initial load.
}
This works well for me. If the user is already on the page and some jQuery functions run, I now know if that user just loaded the page or if they were already on the page.
The easy solution is to use jQuery ‘Once’ plugin
$(element).once('class-name', function() {
// your javascript code
});

What is the recommended ordering of an AJAX load and history.pushState?

For instance, in jQuery, setting up a link to load something into a region, should I load the content before calling history.pushState?
$('#link').click(function () {
$('#region').load('regionContent', function () {
history.pushState(null, null, 'newUrl');
});
return false;
});
Or should I load the content after calling history.pushState?
$('#link').click(function () {
history.pushState(null, null, 'newUrl');
$('#region').load('regionContent');
return false;
});
The former seems preferable to me, because I feel the URL shouldn't change until the content does, but I've seen the latter more often (e.g. https://github.com/blog/760-the-tree-slider), so I'm wondering which is considered best practice.
With both your examples, when the user hits the back button the content isn't going to change! As you haven't got anything inside your state change handler.
Essentially you'll want to do this:
$('#link').click(function () {
History.pushState(null,null,'newUrl');
});
$('body').bind('statechange',function(){
$('#content').load(History.getState().url);
});
This will make it when you click a link, the state of your page will change, and that given the state of your page has changed, it will load in the new content. Hitting the back button in your browser, will also cause the state to change, and thus load in your new content.
Now here I have used History.js's statechange and History.getState().url instead of the native popstate and State.url as different browsers will fire the state change event at different times. For instance safari will the state change event at page load, where chrome and firefox don't - causing in safari your content to load twice. History.js provides a consistent API across all browsers, and if you wish even HTML4 browsers by falling back to hashes.

Is there a way to catch the back button event in javascript?

Is there a way to respond to the back button being hit (or backspace being pressed) in javascript when only the location hash changes? That is to say when the browser is not communicating with the server or reloading the page.
Use the hashchange event:
window.addEventListener("hashchange", function(e) {
// ...
})
If you need to support older browsers, check out the hashChange Event section in Modernizr's HTML5 Cross Browser Polyfills wiki page.
I did a fun hack to solve this issue to my satisfaction. I've got an AJAX site that loads content dynamically, then modifies the window.location.hash, and I had code to run upon $(document).ready() to parse the hash and load the appropriate section. The thing is that I was perfectly happy with my section loading code for navigation, but wanted to add a way to intercept the browser back and forward buttons, which change the window location, but not interfere with my current page loading routines where I manipulate the window.location, and polling the window.location at constant intervals was out of the question.
What I ended up doing was creating an object as such:
var pageload = {
ignorehashchange: false,
loadUrl: function(){
if (pageload.ignorehashchange == false){
//code to parse window.location.hash and load content
};
}
};
Then, I added a line to my site script to run the pageload.loadUrl function upon the hashchange event, as such:
window.addEventListener("hashchange", pageload.loadUrl, false);
Then, any time I want to modify the window.location.hash without triggering this page loading routine, I simply add the following line before each window.location.hash = line:
pageload.ignorehashchange = true;
and then the following line after each hash modification line:
setTimeout(function(){pageload.ignorehashchange = false;}, 100);
So now my section loading routines are usually running, but if the user hits the 'back' or 'forward' buttons, the new location is parsed and the appropriate section loaded.
Check out history.js. There is a html 5 statechange event and you can listen to it.
onLocationChange may also be useful. Not sure if this is a Mozilla-only thing though, appears that it might be.
Did you took a look at this? http://developer.yahoo.com/yui/history/

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