main question
Is there a javascript way to identify if we are accessing a page for the first time or it is a cause of a back?
My problem
I'm implementing html5 navigation in my ajax driven webpage.
On the main script, I initialize a variable with some values.
<script>
var awnsers=[];
process(awnsers);
<script>
Process(awnsers) will update the view according to the given awnsers, using ajax.
In the funciton that calls ajax, and replaces the view, I store the history
history.pushState(state, "", "");
I defined the popstate also, where I restore the view according to the back. Moreover, I modify the global variable awnsers for the old value.
function popState(event) {
if (event.state) {
state = event.state;
awnsers=state.awnsers;
updateView(state.view);
}
}
Navigation (back and forth) goes corectly except when I go to an external page, and press back (arrving to my page again).
As we are accessing the page, first, the main script is called,the valiable awnsers is updated, and the ajax starts. Meanwile, the pop state event is called, and updates the view. After that the main ajax ends, and updates the view according to empty values.
So I need the code:
<script>
var awnsers=[];
process(awnsers);
<script>
only be called when the user enters the page but NOT when it is a back. Any way to do this?
THanks!
Possible solution
After the first awnser I have thought of a possible solution. Tested and works, whoever, I don't know if there is any cleaner solution. I add the changes that I've done.
First I add:
$(function() {
justLoaded=true;
});
then I modify the popState function, so that is in charge to initialize the variables
function popState(event) {
if (event.state) {
state = event.state;
awnsers=state.awnsers;
updateView(state.view);
} else if(justLoaded){
awnsers=[];
process(awnsers);
}
justLoaded=false;
}
Thats all.
what about using a global variable?
var hasLoaded = false;
// this function can be called by dom ready or window load
function onPageLoad() {
hasLoaded = true;
}
// this function is called when you user presses browser back button and they are still on your page
function onBack() {
if (hasLoaded) {
// came by back button and page was loaded
}
else {
// page wasn't loaded. this is first visit of the page
}
}
Use cookie to store the current state.
yeah! This is what I have:
var popped = (($.browser.msie && parseInt($.browser.version, 10) < 9) ? 'state' in window.history : window.history.hasOwnProperty('state')), initialURL = location.href;
$(window).on('popstate', function (event) {
var initialPop = !popped && location.href === initialURL, state;
popped = true;
if (initialPop) { return; }
state = event.originalEvent.state;
if (state && state.reset) {
if (history.state === state) {
$.ajax({url: state.loc,
success: function (response) {
$(".fragment").fadeOut(100, function () {
$(".fragment").html($(".fragment", response).html()).fadeIn(100);
);
document.title = response.match(/<title>(.*)<\/title>/)[1];
}
});
} else { history.go(0); }
else {window.location = window.location.href; }
});
And:
$.ajax({url:link,
success: function (response) {
var replace = args.replace.split(",");
$.each(replace, function (i) {
replace[i] += ($(replace[i]).find("#video-content").length > 0) ? " #video-content" : "";
var selector = ".fragment "+replace[i];
$(selector).fadeOut(100, function () {
$(selector).html($(selector,response).html()).fadeIn(100, function () {
if (base.children("span[data-video]")[0]) {
if ($.browser.msie && parseInt($.browser.version, 10) === 7) {
$("#theVideo").html("");
_.videoPlayer();
} else {
_.player.cueVideoById(base.children("span[data-video]").attr("data-video"));
}
}
});
});
});
document.title = response.match(/<title>(.*)<\/title>/)[1];
window.history.ready = true;
if (history && history.pushState) { history.pushState({reset:true, loc:link}, null, link); }
}
});
Related
I want to disconnect all my users when the tab is closing or the browser is getting closed, so far so good. But when I refresh the page, all my users get disconnected too, this should not happen on refresh. Is it possible to avoid to execute this event on refresh? I saw some users doing with localStorage, but I still didn't get the point.
componentDidMount() {
this.beforeUnloadListener();
}
beforeUnloadListener = () => {
window.addEventListener("beforeunload", (ev) => {
ev.preventDefault();
// code to logout user
});
};
The way beforeunload works, you can not differentiate weather it's a page refresh or a browser close. beforeunload it is a quite confusing event avoid using this.
Hence for cases where you are dealing with the session you should use session storage. The sessionStorage object stores data for only one session (the data is deleted when the browser tab is closed).
Have done this on react application and its work for me on index.html file write this in script tag.
<script type="text/javascript">
window.addEventListener("beforeunload", (event) => {
window.localStorage.isMySessionActive = "true";
});
window.onunload = function (e) {
const newTabCount = localStorage.getItem("tabsOpen");
if (newTabCount !== null) {
localStorage.setItem("tabsOpen", newTabCount - 1);
}
};
</script>
Then go on main file and write this code.
useEffect(() => {
// define increment counter part
const tabsOpen = localStorage.getItem("tabsOpen");
if (tabsOpen == null) {
localStorage.setItem("tabsOpen", 1);
} else {
localStorage.setItem("tabsOpen", parseInt(tabsOpen) + parseInt(1));
}
// define decrement counter part
window.onunload = function (e) {
const newTabCount = localStorage.getItem("tabsOpen");
if (newTabCount !== null) {
localStorage.setItem("tabsOpen", newTabCount - 1);
}
};
if (performance.navigation.type == performance.navigation.TYPE_RELOAD) {
window.localStorage.isMySessionActive = "false";
} else {
const newTabCount2 = localStorage.getItem("tabsOpen");
let value = localStorage.getItem("isMySessionActive");
if (value == "true") {
if (newTabCount2 - 1 == 0) {
localStorage.clear();
window.localStorage.isMySessionActive = "false";
} else {
window.localStorage.isMySessionActive = "false";
}
}
}
}, []);
I am creating a landing page which should exist in two languages. The texts that should be shown are in two JSON files, called accordingly "ru.json" and "en.json". When a user clicks on the "Change language" button, the following function is executed:
function changeLang(){
if (userLang == 'ru') {
userLang = 'en';
document.cookie = 'language=en';
}
else {
userLang = 'ru';
document.cookie = 'language=ru';
}
var translate = new Translate();
var attributeName = 'data-tag';
translate.init(attributeName, userLang);
translate.process();
}
Where Translate() is the following:
function Translate() {
//initialization
this.init = function(attribute, lng){
this.attribute = attribute;
if (lng !== 'en' && lng !== 'ru') {
this.lng = 'en'
}
else {
this.lng = lng;
}
};
//translate
this.process = function(){
_self = this;
var xrhFile = new XMLHttpRequest();
//load content data
xrhFile.open("GET", "./resources/js/"+this.lng+".json", false);
xrhFile.onreadystatechange = function ()
{
if(xrhFile.readyState === 4)
{
if(xrhFile.status === 200 || xrhFile.status == 0)
{
var LngObject = JSON.parse(xrhFile.responseText);
var allDom = document.getElementsByTagName("*");
for(var i =0; i < allDom.length; i++){
var elem = allDom[i];
var key = elem.getAttribute(_self.attribute);
if(key != null) {
elem.innerHTML = LngObject[key] ;
}
}
}
}
};
xrhFile.send();
}
Everything works fine, however, when a user opens the page for the first time, if his Internet connection is bad, he just sees the elements of the page without text. It is just 1-2 seconds, but still annoying.
The question is, is there any way to check the text has loaded and display the page elements only on this condition?
You can use $(document).ready() in this way
$(document).ready(function(){
//your code here;
})
You can use the JavaScript pure load event in this way
window.addEventListener('load', function () {
//your code right here;
}, false);
Source: Here
translate.process() is asynchronous code which needs to make a call to a server and wait for its response. What it means is that, when you call this function, it goes in the background to go do its own thing while the rest of the page continues loading. That is why the user sees the page while this function is still running.
One minimal way I can think around this is by adding this to your css files in the head tag.
body { display: none }
And then, under this.process function, after the for loop ends, add
document.body.style.display = 'block'
If you want to suppori IE8:
document.onreadystatechange = function () {
if (document.readyState == "interactive") {
// run some code.
}
}
Put the code you want to execute when the user initially loads the page in a DOMContentLoaded event handler like below:
document.addEventListener('DOMContentLoaded', function() {
console.log('Whereas code execution in here will be deffered until the initial HTML document has been completely loaded and parsed, without waiting for stylesheets, images, and subframes to finish loading.');
});
console.log('This will log immediatley');
It's important to note that DOMContentLoaded is different than the load event
I'm trying to implement JS history using pushState/popState. Navigating back and forward works just fine, but I have trouble navigating before the initial page load using the browser's back button. It needs 1 extra hit on the browser's back button to leave the page. Why is that?
function action(text) {
history.pushState({"text":text}, text);
doAction(text);
}
function doAction(text) {
$('span').text(text);
}
var $button = $('button');
var $p = $('p');
$p.hide();
action("foo");
$button.on('click', function(){
action("bar");
$button.hide();
$p.show();
})
window.addEventListener("popstate", function(e) {
if (e.state !== null) {
$button.show();
$p.text("Next back should navigate away from this page");
} else {
$p.text("Still here? Why is that? Next back will really navigate away");
}
});
https://jsfiddle.net/lilalinux/p8ewyjr9/20/
Edit: Tested with Chrome OS/X
The initial page load shouldn't use history.pushState because it would add another history entry. There is alredy an implicit first history item with state null.
Using history.replaceState for the initial page load, sets a state for that item but doesn't add another one.
var initialPageLoad = true;
function action(text) {
if (initialPageLoad) {
// replace the state of the first (implicit) item
history.replaceState({"text":text}, text);
} else {
// add new history item
history.pushState({"text":text}, text);
}
initialPageLoad = false;
doAction(text);
}
function doAction(text) {
$('span').text(text);
}
var $button = $('button');
var $p = $('p');
$p.hide();
action("foo");
$button.on('click', function(){
action("bar");
$button.hide();
$p.show();
})
window.addEventListener("popstate", function(e) {
if (e.state !== null) {
$button.show();
$p.text("Next back should navigate away from this page");
// } else {
// won't happen anymore, as the first item has state now
// $p.text("Still here? Why is that? Next back will really navigate away");
}
});
I am using this code to infinite load a page on squarespace. My problem is the reloading doesn't capture the filtering that I have set up in my url. It cannot seem to 'see' the variables or even the url or categoryFilter in my collection. I've tried to use a .var directive but the lazy loaded items cannot see the scope of things defined before it. I'm running out of ideas here please help!
edit: I've since found the answer but gained another question.
I was able to use window.location.href instead of window.location.pathname to eventually get the parameters that way. Except this doesn't work in IE11 so now I have to search for this.
<script>
function infiniteScroll(parent, post) {
// Set some variables. We'll use all these later.
var postIndex = 1,
execute = true,
stuffBottom = Y.one(parent).get('clientHeight') + Y.one(parent).getY(),
urlQuery = window.location.pathname,
postNumber = Static.SQUARESPACE_CONTEXT.collection.itemCount,
presentNumber = Y.all(post).size();
Y.on('scroll', function() {
if (presentNumber >= postNumber && execute === true) {
Y.one(parent).append('<h1>There are no more posts.</h1>')
execute = false;
} else {
// A few more variables.
var spaceHeight = document.documentElement.clientHeight + window.scrollY,
next = false;
/*
This if statement measures if the distance from
the top of the page to the bottom of the content
is less than the scrollY position. If it is,
it's sets next to true.
*/
if (stuffBottom < spaceHeight && execute === true) {
next = true;
}
if (next === true) {
/*
Immediately set execute back to false.
This prevents the scroll listener from
firing too often.
*/
execute = false;
// Increment the post index.
postIndex++;
// Make the Ajax request.
Y.io(urlQuery + '?page=' + postIndex, {
on: {
success: function (x, o) {
try {
d = Y.DOM.create(o.responseText);
} catch (e) {
console.log("JSON Parse failed!");
return;
}
// Append the contents of the next page to this page.
Y.one(parent).append(Y.Selector.query(parent, d, true).innerHTML);
// Reset some variables.
stuffBottom = Y.one(parent).get('clientHeight') + Y.one(parent).getY();
presentNumber = Y.all(post).size();
execute = true;
}
}
});
}
}
});
}
// Call the function on domready.
Y.use('node', function() {
Y.on('domready', function() {
infiniteScroll('#content','.lazy-post');
});
});
</script>
I was able to get this script working the way I wanted.
I thought I could use:
Static.SQUARESPACE_CONTEXT.collection.itemCount
to get {collection.categoryFilter} like with jsont, like this:
Static.SQUARESPACE_CONTEXT.collection.categoryFilter
or this:
Static.SQUARESPACE_CONTEXT.categoryFilter
It didn't work so I instead changed
urlQuery = window.location.pathname
to
urlQuery = window.location.href
which gave me the parameters I needed.
The IE11 problem I encountered was this script uses
window.scrollY
I changed it to the ie11 compatible
Window.pageYOffset
and we were good to go!
I've created a Backbone, Marionette and Require.js application and am now trying to add smooth transitioning between regions.
To do this easily* ive decided to extend the marionette code so it works across all my pages (theres a lot of pages so doing it manually would be too much)
Im extending the marionette.region open and close function. Problem is that it now doesnt call the onClose function inside each of my views.
If I add the code directly to the marionette file it works fine. So I'm probably merging the functions incorrectly, right?
Here is my code:
extendMarrionette: function () {
_.extend(Marionette.Region.prototype, {
open : function (view) {
var that = this;
// if this is the main content and should transition
if (this.$el.attr("id") === "wrapper" && document.wrapperIsHidden === true) {
this.$el.empty().append(view.el);
$(document).trigger("WrapperContentChanged")
} else if (this.$el.attr("id") === "wrapper" && document.wrapperIsHidden === false) {
$(document).on("WrapperIsHidden:open", function () {
//swap content
that.$el.empty().append(view.el);
//tell router to transition in
$(document).trigger("WrapperContentChanged");
//remove this event listener
$(document).off("WrapperIsHidden:open", that);
});
} else {
this.$el.empty().append(view.el);
}
},
//A new function Ive added - was originally inside the close function below. Now the close function calls this function.
kill : function (that) {
var view = this.currentView;
$(document).off("WrapperIsHidden:close", that)
if (!view || view.isClosed) {
return;
}
// call 'close' or 'remove', depending on which is found
if (view.close) {
view.close();
}
else if (view.remove) {
view.remove();
}
Marionette.triggerMethod.call(that, "close", view);
delete this.currentView;
},
// Close the current view, if there is one. If there is no
// current view, it does nothing and returns immediately.
close : function () {
var view = this.currentView;
var that = this;
if (!view || view.isClosed) {
return;
}
if (this.$el.attr("id") === "wrapper" && document.wrapperIsHidden === true) {
this.kill(this);
} else if (this.$el.attr("id") === "wrapper" && document.wrapperIsHidden === false) {
//Browser bug fix - needs set time out
setTimeout(function () {
$(document).on("WrapperIsHidden:close", that.kill(that));
}, 10)
} else {
this.kill(this);
}
}
});
}
Why don't you extend the Marionette.Region? That way you can choose between using your custom Region class, or the original one if you don't need the smooth transition in all cases. (And you can always extend it again if you need some specific behavior for some specific case).
https://github.com/marionettejs/backbone.marionette/blob/master/docs/marionette.region.md#region-class
var MyRegion = Marionette.Region.extend({
open: function() {
//Your open function
}
kill: function() {
//Your kill function
}
close: function() {
//Your close function
}
});
App.addRegions({
navigationRegion: MyRegion
});
Perhaps your issue is that you are not passing a function to your event listener, but instead calling the code directly in the code below.
setTimeout(function(){
$(document).on("WrapperIsHidden:close", that.kill(that));
}, 10)
It is likely that you want something like this:
setTimeout(function(){
$(document).on("WrapperIsHidden:close", function (){ that.kill(that); });
}, 10)
Another possible problem is that you are mixing up your references to this/that in your kill function. It seems like you probably want var view to either be assigned to that.view or to use this rather than that throughout the method.
Answer to your additional problems:
You should try passing the view variable from the close function directly into your kill function because the reference to currentView is already changed to the new view object when you actually want to old view object. The reason this is happening is that you are setting a timeout before executing the kill function. You can see this if you look at the show source code. It expects close, open and then currentView assignment to happen synchronously in order.