Develop Reference

Replace a "Click to load more" into a Scroll to load more

Currently, my client's website has a "Load more" button, linked to the Shutterstock API to load more photos everytime you click on that button.
My client asked to change this into "When the user scrolls down, it loads automatically more images".
So what I thought, since I'm not an experienced coder, is to add a function linked with window.scroll that would trigger a click on that button once you reach the top of that button, using the following code:
$(window).scroll(function() {
var top_of_element = $("#load_more_images").offset().top;
var bottom_of_element = $("#load_more_images").offset().top + $("#load_more_images").outerHeight();
var bottom_of_screen = $(window).scrollTop() + window.innerHeight;
var top_of_screen = $(window).scrollTop();
if((bottom_of_screen > top_of_element) && (top_of_screen < bottom_of_element)){
$("#load_more_images").trigger("click");
}
else {
// The element is not visible, do something else
}
});
The issue, is that once the button is in view, it triggers the click multiple time, and it loads the next 6 images multiple times back to back. I guess it's clicking multiple time since the button stays in view, not sure how to handle this.
The code for the "load more" function that works linked to that "load_more_images" button is in a "func.php" page (it's for a Wordpress site, and it's in a plugin) :
jQuery("#load_more_images").click(function() {
jQuery(this).hide();
jQuery(".load_more_wrapper .loader").show();
var ajax_url = "'.admin_url('admin-ajax.php').'";
jQuery.post(
ajax_url,
{
"action": "pd_load_more_img",
"data": {
"type": search_type,
"page":page+1,
"image_type": "'.(isset($_GET["image_type"]) ? $_GET["image_type"] : "all").'"';
if (isset($_GET['category'])){
$js.=',
"category":'.$_GET['category'];
}
if (isset($_GET['search'])){
$js.=',
"search":"'.$_GET['search'].'"';
}
$js.= '}
},
function(data){
page++;
jQuery("#images_container").append(data);
jQuery(".load_more_wrapper .loader").hide();
jQuery("#load_more_images").show();
jQuery(".category-link").dotdotdot();
}
);
});';
Any idea how I could make this work? All I need is to activate that existant function that is currently bound to a click event, but on scroll, when I reach that button, or a certain element in the page at the bottom.
Thanks a lot

You can use that function instead of your click function:-
$(window).scroll( function(e){ if($(window).scrollTop()>= jQuery('#load_more_images').position().top){ doYourFunctionHere(); } }

Browser back button with divs hidden with css

I have a website where real estate properties search results are displayed like using <div>s with just 6 displayed by default and "load more" button. When user clicks Load more button, 9 more posts displayed, etc. How it is done: divs are hidden by default (display: none;) and then .show class is added to the next 9 items.
a("span.more-search-items").on("click", function(t) {
t.preventDefault();
var e = a(this).parents(".property-search");
e.find(".prop").not(".show").slice(0, 9).each(function() {
var t = a(this).attr("data-img");
a(this).css("background-image", "url(" + t + ")"), a(this).find(".main-image").attr("src", t), a(this).addClass("show")
}), 0 == e.find(".prop").not(".show").length && a("span.more-search-items").hide();
e.find(".prop.show").length
When user goes to single property and then hits back browser button, it shows the first 6 items again. I tried to implement history.pushState() method there where URL changes for each "load more" button click:
var href = window.location.href.replace(window.location.hash, '');
var currentPage = location.hash.replace("#","");
history.pushState(null, null, href + "#" + (+currentPage + 1));
URL changes but the story is still the same - only first 6 results are being displayed when user goes back in history. Is there something I can do in this situation?

If you need to deal with History API you need
on load more click you need to push or replace the history with something like the numbers of visible divs with hash #15 , #24 something like this
With push/replace state you need to use $(window).on('popstate' , function(){ alert(window.location.hash); }) and while user goes to single property it refresh all the page and when browser back button clicked it returns and refreshes the previous page .. so you need to check alert(window.location.hash); when page load
Finally when you got an alert with the number from window.location.hash you can then show the divs depending on it
Ok let me explain this for you in code
$(document).ready(function(){
alert(window.location.hash); // check the alert here
$('.load_more_button').on('click' , function(){
if(window.location.hash){
var href = window.location.href.split('#');
var currentPage = parseInt(window.location.hash);
history.pushState(null, null, href[0] + "#" + (+currentPage + 1));
}
});
$(window).on('popstate' , function(){
alert(window.location.hash); // check the alert here
});
});
You can start from here when you get the number do as you like

Photoswipe pswp class Not Clearing After Closing Image

I have a Photoswipe (http://photoswipe.com) image gallery on my site, and the css class is not resetting/clearing to remove the view after I close a gallery for the second time.
ex.
User opens item 1, AJAX populates the figure(s) into the picture div.
User clicks an image from item 1 and Photoswipe opens the image properly (setting the following class):
class="pswp pswp--supports-fs pswp--open pswp--animate_opacity pswp--notouch pswp--css_animation pswp--svg pswp--animated-in pswp--visible"
User closes the image from item 1, class resets as normal:
class="pswp"
User closes item 1 and JS/JQuery clears all html in picture div. User opens item 2, AJAX populates the figure into the picture div. User clicks an image from item 2 and Photoswipe opens the image properly setting the same class as before.
class="pswp pswp--supports-fs pswp--open pswp--animate_opacity pswp--notouch pswp--css_animation pswp--svg pswp--animated-in pswp--visible"
This is where the problem occurs. User closes the image from item 2 and the only thing that changes is:
aria-hidden="true"
but the class does not clear, it remains:
class="pswp pswp--supports-fs pswp--open pswp--animate_opacity pswp--notouch pswp--css_animation pswp--svg pswp--animated-in pswp--visible"
when it should change to:
class="pswp"
This disables all interaction on the website since there is an invisible div/class on top of everything. The class needs to be changed back to pswp somehow.
AJAX/JS To Populate picture div (I added an id to the div):
if (i == 0) {
$('#listing_photos_container').append('<figure itemprop="associatedMedia" itemscope itemtype="http://schema.org/ImageObject"><img src="' + json[i].image_url + '" height="400" width="600" itemprop="thumbnail" alt="listingPhoto" class="listing-photo"></figure>');
} else {
$('#listing_photos_container').append('<figure itemprop="associatedMedia" itemscope itemtype="http://schema.org/ImageObject" class="listing-photo-holder"><img src="' + json[i].image_url + '" height="400" width="600" itemprop="thumbnail" alt="listingPhoto" class="listing-photo-holder"></figure>');
}
JS/JQuery to clear photo div:
$('#listing_photos_container').html('');
EDIT: The click listener function is running twice when a users clicks the photo to bring full screen. This is the code for the listener:
$.ajax({
type: "POST",
url: 'http://example.com/action?action=photos',
data: {id: id},
success: function (data) {
console.log('API Call - Photos');
json = JSON.parse(data);
$('#listing_photos_container').html('');
for (var i = 0; i < json.length; i++) {
// Styling code here
}
$('#list_header').html(
(function($) {
$('.picture').each( function() {
var $pic = $(this),
getItems = function() {
var items = [];
$pic.find('a').each(function() {
var $href = $(this).attr('href'),
$size = $(this).data('size').split('x'),
$width = $size[0],$height = $size[1];
var item = {
src : $href,
w : $width,
h : $height
}
items.push(item);
});
return items;
}
var items = getItems();
console.log('Items for PSWP' + items);
alert('Alert Point 1'); // This is called once, (as it should).
var $pswp = $('.pswp')[0];
$pic.on('click', 'figure', function(event) {
// This block is called twice..
alert('Click Funct');
event.preventDefault();
var $index = $(this).index();
var options = {
index: $index,
bgOpacity: 0.7,
showHideOpacity: true
}
// Initialize PhotoSwipe
alert('Setting new PhotoSwipe');
var lightBox = new PhotoSwipe($pswp, PhotoSwipeUI_Default, items, options);
lightBox.init();
}); // End $pic.on
});// End .picture each
})(jQuery)
); // End list_header.html
} // End AJAX Success
}); // End AJAX

You may have already fixed this, but in case someone else falls upon this.
This can happen if you trigger opening the gallery more than once without closing it. It may be that you have registered multiple click handlers to open the gallery or for some reason the event is being fired twice.
It happens because in the init function the current class name of the pswp element is retrieved and cached, then on destroy the class name is restored. When the second open occurs without destroy being called _initialClassName will be set to class="pswp pswp--supports-fs pswp--open pswp--animate_opacity pswp--notouch pswp--css_animation pswp--svg pswp--animated-in pswp--visible" as your are seeing
Line 776 of photoswipe.js where initialclass is set
_initalClassName = template.className;
Breakpoint this in your browser to see if it is called multiple times when opening
Line 942 onwards destroy function
destroy: function() {
_shout('destroy');
Breakpoint this in your browser to ensure it is being called for every time open is called
Final Solution
The problem is that when opening the popup and loading the images you are filling #listing_photos_container with your photos, then adding a click handler to open photoswipe. This click handler is added to the top element, so will remain when the popup is closed, then the next time it is opened a new click handler will be added.
To fix this you just need to unbind the click handler when closing the popup, you can do this with $(".picture").off('click'); somewhere inside your closeListing() function

It's quite simple, before every .click(...) you need to write .unbind('click').
Example:
$('a#open-photoswipe').unbind('click').click(function() {
// open photoswipe here
});

Was having similar problem - just define lightBox as global variable. And on destroy define it as null. And in beginning of function where You initialize lightBox just check if lighBox is already defined, then do return.

Switching style between two elements on photo gallery change

So I have a photo gallery on my front page that switches between two images; each image links to a different page. Now, beside that gallery I have two links that go to the same two pages. The idea is that when image A is showing, side-link A should be highlighted with a border. The issue I keep running into is that once I get either side-link to be highlighted, I don't really know how to get it unhighlighted. Instead of switching with the images, they just stay highlighted.
var debugLink = "#firstLink";
function displayNextImage()
{
index++;
if(index >= indexgalpics.length)
{
index=0;
}
//---this is where I set the var debugLink which is
// supposed to carry the selected linke
if(index == 0)
{
console.log("first link selected");
//---when image A is showing, top side-link should be highlighted
//---ok so we know this much works, it seems these double equal
// signs are very important here.
//---makeActive();
//---but once makeActive() is called here, it makes the first link
// active for the entire time.
//---we can't put the entire style code here because same as before,
// it just keeps the link highlighted forever
debugLink = "#firstLink";
//---ok so i can set a var at top to a value in the makeActive() function,
// but i think the way JS works highlights either one forever
debugLink = "#firstLink";
}
else if(index == 1)
{
console.log("second link should be selected");
//---when image B is showing, bottom side-link should be highlighted
debugLink = "#secondLink";
}
showImg();
}
function makeActive()
{
var activeLink = document.querySelector(debugLink);
//---adds style to the debugLink
}
The function makeActive() is called in the function showImg(), and the function displayNextImage() is called in another function that sets the timer.

I changed your approach a little bit by using a boolean for the index, because you seem to only need two states.
Here is a revised version:
Note: In this code, I've used custom-made functions to make the code easier to read. I created hasClass(el,class), addClass(el,class), removeClass(el,class), toggleClass(el,class,bool). You can find them in the final JS Fiddle.
// Register the link elements
var links = {
true : document.getElementById('firstLink'),
false : document.getElementById('secondLink')
},
// Keep track of selected link (replaces your 'index')
leftLinkActive = false,
// Just so you don't go get it every time
gallery = document.getElementById('gallery');
// Let's trigger the gallery
displayNextImage();
// We'll change the active link and show the correct image
function displayNextImage(){
leftLinkActive = !leftLinkActive;
if(leftLinkActive){ console.log("first link selected"); }
else{ console.log("second link selected"); }
makeActive();
showImg();
// Let's do that again in 2 seconds
setTimeout(displayNextImage,2000);
}
// Add / remove the active class
function makeActive(){
addClass( links[ leftLinkActive ], 'active-class');
removeClass( links[ !leftLinkActive ], 'active-class');
}
// Change the image with a small fadeOut transition
function showImg(){
addClass(gallery,'fadeOut');
setTimeout(function(){
// Here we switch from img1 and img2
gallery.style.backgroundImage = 'url('+(leftLinkActive?'im1.jpg':'im2.jpg')+')';
removeClass(gallery,'fadeOut');
},200);
}
JS Fiddle Demo

Preventing reloading Ajax data when back-button is clicked in both Chrome and IE

I am currently working on a website in which the home page displays the most recent 10 blog entries. When I scroll down, and when I reach almost the end of the last item on screen, another 10 blog entries are automatically loaded, and so on (this is the infinite scrolling feature).
If a user clicks on any blog entry, then he/she is taken to another page to display the details about that blog entry. When the user clicks the back button, he/she is taken to the home page that has the entries displayed.
Please note, the home page loads the data using Ajax.
Assume the following scenario:
A user goes to the site, and entries 1 to 10 are loaded (via Ajax).
The user scrolls down, and the next 10 entires, specifically entries 11 to 20 are loaded (via Ajax as well). Note that the page now has entires 1 to 20 displayed.
The user scrolls further down, and now entries 21 through 30 are loaded, for a total of 1 through 30 blog entries being displayed on the page.
The user clicks on entry 25, and the page for entry 25 is displayed.
The user clicks the back button, and all items, 1 through 30 are displayed.
Now, if the users uses FireFox, Opera, or Safari, and when that user performs step 5 (i.e, clicks the back button to go back to the home page) then the blog entries are just displayed on screen, and without being re-loaded. However using IE and on Chrome, when the user clicks on the back button, the page is reloaded, and only items 1 through 10 are displayed.
I do not like the IE and Chrome behaviour. The user should see items 1 though 30. How can I ensure all browsers behave like FireFox?
Thanks.
Update
Here is the code I am using
First, hers is my html
<html>
<body>
<section id="content">
<section id="articles">
<!-- This section is filled by jQuery/Ajax -->
</section>
<section id="loading-spinner">
<img src="ajax-loader.gif" />
</section>
</section>
</body>
</html>
And here is my jQuery
/**
*
* This file uses a bunch of programming concepts, but the most important one is ensuring ajax calls run as a critical section
* ... (this means if ajax is already called, then another instance of JavaScript cannot get into the critical section)
*
* .. For more details, please read: http://stackoverflow.com/questions/22150960/critical-section-in-javascript-or-jquery
*
*/
load_more_posts = function () {
// If we almost reach the bottom of the document, then load more posts
if ( jQuery(window).scrollTop() >= jQuery(document).height() - jQuery(window).height() - 300) {
// If the value of the promise is not pending, then we can call the load_posts function (the load_posts function will change the status to pending when it is executing the ajax request)
if (ajax_status.state() !== "pending") {
load_posts();
}
}
};
function load_posts() {
ajax_status = jQuery.ajax({
type: 'post',
dataType: 'json',
beforeSend: function(xhr) {
if(jQuery.data(document.body, 'load_page') == false) {
xhr.abort();
}
else {
// Show the spinner
jQuery('#loading-spinner').visible();
}
},
url: '../link/to/get_poasts.php',
data: {
action: 'load_posts',
js_query_data: query_data,
js_page: jQuery.data(document.body, 'page_to_load')
},
success: function (response) {
if (response.isSuccessful) {
var number_of_post_items = response.posts_array.length;
for (var i = 0; i < number_of_post_items; i++) {
// If the item is already returned from the database and posted. then we skip it, otherwise, keep insert a new record
if (jQuery('#articles').find('#article-' + response.posts_array[i].post_id).length == 0) {
// Add 'article'
jQuery('#articles').append('<article id="article-' + response.posts_array[i].post_id + '"></article>');
// More code here to add details about each article, such as title, excerpt...etc.
}
}
// Increase the value of the page to load by 1, and save it.
page = jQuery.data(document.body, "page_to_load");
page = page + 1;
jQuery.data(document.body, "page_to_load", page);
jQuery(window).on('scroll', load_more_posts);
}
else {
// Display error message
jQuery('#articles').append('<div>' + response.message + '</div>');
// Make sure no further AJAX requests are made
jQuery.data(document.body, 'load_page', false);
}
}
}).always(function() {
// Hide the spinner
jQuery('#loading-spinner').invisible();
});
return ajax_status;
}
// Create a new promise. This will be used to ensure that no two calls hit the critical section at the same time
// ... (the critical section in this case is the time when we retrieve data from the database. We only want one call at a time)
var ajax_status = new jQuery.Deferred();
jQuery(document).ready(function() {
// Hide the loading spinner first
jQuery('#loading-spinner').invisible();
// We resolve the promise, making sure it is ready (this is an intial state)
ajax_status.resolve();
// Initial values that are used
jQuery.data(document.body, 'page_to_load', 1);
// This parameter is used to stop loading pages when no more items are available to be displayed
jQuery.data(document.body, 'load_page', true);
// Initial loading of poasts
load_posts();
// Enable on scrolling to load more pasts (to allow infinite scrolling)
jQuery(window).on('scroll', load_more_posts);
});

You'll find some information about how it works in the "good" browsers in this answer:
Is there a cross-browser onload event when clicking the back button?
Here you'll find a way to emulate it in IE:
Differences in Internet Explorer and Firefox when dynamically loading content then going forward and back
Not quite sure why it doesn't work in Chrome though.

Just so everyone knows, here is the solution I came up with that is consistent in all browsers. Unfortunately this solution requires a reloead/refresh button to reload the data. I tried to avoid that but could not. Until both IE and Chrome tackle the bfcache issue, I will stick to this solution.
First, here is the new html
<html>
<body>
<section id="content">
<a id="refresh">
<img src="link/to/refresh.png" title="Refresh" alt="refresh" />
</a>
<section id="articles">
<!-- This section is filled by jQuery/Ajax -->
</section>
<section id="loading-spinner">
<img src="ajax-loader.gif" />
</section>
</section>
</body>
</html>
And this is the javascript
/**
*
* This file uses a bunch of programming concepts, but the most important one is ensuring ajax calls run as a critical section
* ... (this means if ajax is already called, then another instance of JavaScript cannot get into the critical section)
*
* .. For more details, please read: http://stackoverflow.com/questions/22150960/critical-section-in-javascript-or-jquery
*
*/
load_more_posts = function () {
// If we almost reach the bottom of the document, then load more posts
if ( jQuery(window).scrollTop() >= jQuery(document).height() - jQuery(window).height() - 300) {
// If the value of the promise is not pending, then we can call the load_posts function (the load_posts function will change the status to pending when it is executing the ajax request)
if (ajax_status.state() !== "pending") {
load_posts();
}
}
};
function load_posts() {
ajax_status = jQuery.ajax({
type: 'post',
dataType: 'json',
beforeSend: function(xhr) {
if(jQuery.data(document.body, 'load_page') == false) {
xhr.abort();
}
else {
// Show the spinner
jQuery('#loading-spinner').visible();
}
},
url: '../link/to/get_poasts.php',
data: {
action: 'load_posts',
js_query_data: query_data,
js_page: sessionStorage.getItem("page_to_load")
},
success: function (response) {
if (response.isSuccessful) {
var number_of_post_items = response.posts_array.length;
for (var i = 0; i < number_of_post_items; i++) {
// If the item is already returned from the database and posted. then we skip it, otherwise, keep insert a new record
if (jQuery('#articles').find('#article-' + response.posts_array[i].post_id).length == 0) {
// Add 'article'
jQuery('#articles').append('<article id="article-' + response.posts_array[i].post_id + '"></article>');
// More code here to add details about each article, such as title, excerpt...etc.
var history_session = get_history_session_name();
var history = sessionStorage.getItem(history_session);
var article_content = jQuery('#articles').find('#aarticle-' + response.posts_array[i].post_id)[0].outerHTML;
sessionStorage.setItem(history_session, history + article_content);
}
}
// Increase the value of the page to load by 1, and save it.
page = parseInt(sessionStorage.getItem("page_to_load"));
page = page + 1;
sessionStorage.setItem("page_to_load", page);
jQuery(window).on('scroll', load_more_posts);
}
else {
// Display error message
jQuery('#articles').append('<div>' + response.message + '</div>');
// Make sure no further AJAX requests are made
jQuery.data(document.body, 'load_page', false);
}
}
}).always(function() {
// Hide the spinner
jQuery('#loading-spinner').invisible();
});
return ajax_status;
}
function get_history_session_name () {
session_name = 'history___' + escape(location.href);
return session_name;
}
// Create a new promise. This will be used to ensure that no two calls hit the critical section at the same time
// ... (the critical section in this case is the time when we retrieve data from the database. We only want one call at a time)
var ajax_status = new jQuery.Deferred();
jQuery(document).ready(function() {
// Hide the loading spinner first
jQuery('#loading-spinner').invisible();
// We resolve the promise, making sure it is ready (this is an intial state)
ajax_status.resolve();
// This parameter is used to stop loading pages when no more items are available to be displayed
jQuery.data(document.body, 'load_page', true);
// Get the name of the history session
var history_session = get_history_session_name();
if (sessionStorage.getItem(history_session) === null) {
// Set the history session storage
sessionStorage.setItem(history_session, "");
// Initial values that are used
sessionStorage.setItem("page_to_load", 1);
// Load the posts
load_posts();
}
// Load from history when the back button is clicked
else {
jQuery('#articles').append(sessionStorage.getItem(history_session));
}
// Enable on scrolling to load more pasts (to allow infinite scrolling)
jQuery(window).on('scroll', load_more_posts);
// Reload data when the refresh button is clicked
// ... We are using a refresh button because if we go to a page that already had history, ...
// ... and even though we went to that page without using the back button (i.e, via links or directly via the url), ...
// ... then the history session will be displayed. ...
// ... Therefore a reload button is needed to overcome this problem if you like to reload data
jQuery("#refresh").click(function () {
// Reset/clear the articles section first
jQuery('#articles').html("");
// reset the 'load_page' variable
jQuery.data(document.body, 'load_page', true);
// Reset/clear the history session storage
sessionStorage.setItem(history_session, "");
// Start with loading page 1
sessionStorage.setItem("page_to_load", 1);
// Load the posts
load_posts();
});
});
Hope this helps.