Develop Reference

Javascript onclick event firing for id but not for class

I'm fairly new to Javascript, and am trying to get an 'on click enlarge' kind of effect, where clicking on the enlarged image reduces it again. The enlarging happens by replacing the thumbnail by the original image. I also want to get a slideshow using images from my database later on.
In order to do that, I made a test where I replace the id which indicates enlarging is possible by a class and I also use a global variable so that I can keep a track of the url I'm using. Not sure this is the best practice but I haven't found a better solution.
The first part works fine, my image gets changed no problem, values are also updated according to the 'alert' statement. However, the second part, the one with the class never triggers.
What am I doing wrong (apart from the very likely numerous bad practices) ?
If instead of changing the class I change the id directly (replacing .image_enlarged by #image_enlarged, etc.), it seems to call the first function, the one with the id, yet outputs the updated id, which is rather confusing.
var old_url = "";
$(function(){
$('#imageid').on('click', function ()
{
if($(this).attr('class')!='image_enlarged'){
old_url = $(this).attr('src');
var new_url = removeURLPart($(this).attr('src'));
$(this).attr('src',new_url); //image does enlarge
$(this).attr('class',"image_enlarged");
$(this).attr('id',"");
alert($(this).attr('class')); //returns updated class
}
});
$('.image_enlarged').on('click', function (){
alert(1); //never triggered
$(this).attr('src',old_url);
$(this).attr('class',"");
$(this).attr('id',"imageid");
});
});
function removeURLPart(e){
var tmp = e;
var tmp1 = tmp.replace('thumbnails/thumbnails_small/','');
var tmp2 = tmp1.replace('thumbnails/thumbnails_medium/','');
var tmp3 = tmp2.replace('thumbnails/thumbnails_large/','');
return tmp3;
}
As for the html, it's really simple :
<figure>
<img src = "http://localhost/Project/test/thumbnails/thumbnails_small/image.jpg" id="imageid" />
<figcaption>Test + Price thing</figcaption>
</figure>
<script>
document.write('<script src="js/jquery-1.11.1.min.js"><\/script>');
</script>
<script type="text/javascript" src="http://localhost/Project/js/onclickenlarge.js"></script>

From the API: http://api.jquery.com/on/
The .on() method attaches event handlers to the currently selected
set of elements in the jQuery object.
When you do $('.image_enlarged').on(...) there is no element with that class. Therefore, the function is not registered in any element.
If you want to do so, then you have to register the event after changing the class.
Here's an example based on your code: http://jsfiddle.net/8401mLf4/
But this registers the event multiple times (every time you click) and it would be wrong. So I would do something like:
$('#imageid').on('click', function () {
if (!$(this).hasClass('image_enlarged')) {
/* enlarge */
} else {
/* restore */
}
}
JSfiddle: http://jsfiddle.net/8401mLf4/2/

Try using:
addClass('image-enlarged')
instead of:
.attr('class',"image_enlarged");
the best way to do this would be to have a small-image class and a large image class that would contain the desired css for both and then use addClass() and removeClass depending on which you wanted to show.

Problems getting values into a dynamic variable in javascript

selectedsong div has differents links with differents rel=""... and the problems is...
I'm using that:
selectedBtn = $('#selectedsong a');
selectedBtn.click(function()
{
self.selectedsong($(this).attr('rel'));
return false;
});
selectedsong: function(number)
{
$('#selectedsong').html('new content with new links, rel, and more...');
selectedBtn = $('#selectedsong a'); <---- THE PROBLEM IS HERE,
}
The problem is that, in the first click it works properly, but when the #selectedsong content change, selectedBtn = $('#selectedsong a'); don't work properly, because the selectedBtn.click(function() doesn't work :'(
Thank you very much!

Use
$('#selectedsong').on('click','a',function(e)
{
e.preventDefault(); // prevent default behavior of anchor click
self.selectedsong($(this).attr('rel'));
//return false; dont use return false as it does more work than you need
});
selectedsong: function(number)
{
$('#selectedsong').html('new content with new links, rel, and more...');
}
As your HTML content changes you need to use event delegation.
read more on .on()

I think the problem is that you changed the html inside #selectedsong, and that removed your <a> tag from it, and that's what you're trying to do a select on, is the <a> tag inside #selectedsong. Maybe you could try and just select #selectedsong instead of the anchor tag? Or when you change the html, change the html of #selectedsong a.

Transferring Onclick Function to jQuery

I have a jQuery function that replaces thumbnails with the main image.
This is the code that I use for replacing the main image:
$(document).ready(function(){
$(".wheelFinishThumbs a").click(function() {
var mainImage = $(this).attr("href");
var mainTemp = mainImage.replace(/-mid/,'');
var mainTemp = mainTemp.replace(/png/,'jpg');
$("#main_view img").attr('src', mainImage );
$("#main_view a").attr('href',mainTemp);
return false;
});
I use a PHP function to download (save) images by changing their header values. This is the HTML code that I use to download images
Click to download
but since "image.jpg" has to be my dynamic variable some how I've got to call this argument in the jQuery image replacement function and replace "image.jpg" dynamically each time I change the main image. I want to replace image.jpg with var mainImage from my image swapping function.
My jQuery knowledge is really limited, so If somebody can help me to do it, would be great.

This should work, assuming you are using jQuery 1.7+
Assuming your a tag markup is like this after you dynamically set the href to new image
Download Image
JavasScript
$(function(){
$(document).on("click","#main_view",function(e){
e.preventDefault();
var self=$(this);
alert("replace this with awesome code")
window.open('download.php?file='+self.attr("href")+,'_self', 'download', 'status=0');
});
});
Note that this function will work only of a single a element because we are targeting binding the functionality to the element with id main_view. Since ID's should be unique in the DOM, If you want to have the functionality to many a tags, i would add a common class selector to the a tag like this
<a class="aDownloadble" href="urltoSomeImage2.jpg" id="main_view">Download Image2</a>
<a class="aDownloadble" href="urltoSomeImage4.jpg" id="main_view">Download Image4</a>
And Update my script like this
$(function(){
$(document).on("click",".aDownloadble",function(e){
e.preventDefault();
var self=$(this);
alert("replace this with awesome code")
window.open('download.php?file='+self.attr("href"),'_self', 'download', 'status=0');
});
});
jQuery on is nnot necessary. you can simply use the click event binding directly. But if you are loading the markup of those links via ajax / injecting to the DOM dynamically, you should use on or live.

$(document).ready(){
$("#main_view a").click(function() {
// Code to run when user clicks on link
});
});

Load Html Content if not exist JQuery AJAX

I have a page with 3 buttons. >Logos >Banners >Footer
When any of these 3 buttons clicked it does jquery post to a page which returns HTML content in response and I set innerhtml of a div from that returned content . I want to do this so that If I clicked Logo and than went to Banner and come back on Logo it should not request for content again as its already loaded when clicked 1st time.
Thanks .

Sounds like to be the perfect candidate for .one()
$(".someItem").one("click", function(){
//do your post and load the html
});
Using one will allow for the event handler to trigger once per element.

In the logic of the click handler, look for the content having been loaded. One way would be to see if you can find a particular element that comes in with the content.
Another would be to set a data- attribute on the elements with the click handler and look for the value of that attribute.
For example:
$(".myElements").click(function() {
if ($(this).attr("data-loaded") == false {
// TODO: Do ajax load
// Flag the elements so we don't load again
$(".myElements").attr("data-loaded", true);
}
});
The benefit of storing the state in the data- attribute is that you don't have to use global variables and the data is stored within the DOM, rather than only in javascript. You can also use this to control script behavior with the HTML output by the server if you have a dynamic page.

try this:
HTML:
logos<br />
banner<br />
footer<br />
<div id="container"></div>
JS:
$(".menu").bind("click", function(event) {
event.stopPropagation();
var
data = $(this).attr("data");
type = $(this).attr("type");
if ($("#container").find(".logos").length > 0 && data == "logos") {
$("#container").find(".logos").show();
return false;
}
var htmlappend = $("<div></div>")
.addClass(type)
.addClass(data);
$("#container").find(".remover-class").remove();
$("#container").find(".hidde-class").hide();
$("#container").append(htmlappend);
$("#container").find("." + data).load("file_" + data + "_.html");
return false;
});

I would unbind the click event when clicked to prevent further load requests
$('#button').click(function(e) {
e.preventDefault();
$('#button').unbind('click');
$('#result').load('ajax/test.html ' + 'someid', function() {
//load callback
});
});
or use one.click which is a better answer than this :)

You could dump the returned html into a variable and then check if the variable is null before doing another ajax call
var logos = null;
var banners = null;
var footer = null;
$(".logos").click(function(){
if (logos == null) // do ajax and save to logos variable
else $("div").html(logos)
});

Mark nailed it .one() will save extra line of codes and many checks hassle. I used it in a similar case. An optimized way to call that if they are wrapped in a parent container which I highly suggest will be:
$('#id_of_parent_container').find('button').one("click", function () {
//get the id of the button that was clicked and do the ajax load accordingly
});

Calling Javascript in a page after it's been loaded by jQuery GET

Imagine a normal page calling javscript in head. The trouble is some of the content isnt loaded untill i click on a link. Subsequently when this link loads the content it wont work. This is because i guess the javascript has already been run and therefor doesnt attach itself to those elements called later on. There is only standard html being called.
So for example this is the code which calls my external html.
$.get('content.inc.php', {id:id}, function(data){
$('#feature').children().fadeTo('fast', 0).parent().slideUp('slow', function(){
$(this).html(data).slideDown('slow');
});
});
If the html i was calling for example and H1 tag was already in the page the cufon would work. However because i am loading the content via the above method H1 tags will not be changed with my chosen font.This is only an example. The same will apply for any javascript.
I was wonering whether there is a way around this without calling the the javascript as well the html when its received from the above function

If you want to attach events to elements on the page that are dynamically created take a look at the "live" keyword.
$('H1').live("click", function() { alert('it works!'); });
Hope this is what you were looking for.

Does Cufon.refresh() do what you want?
As you said Cufon was just an example, I'd also suggest a more general:
$.get(url, options, function(html, status) {
var dom = $(html);
// call your function to manipulate the new elements and attach
// event handlers etc:
enhance(dom);
// insert DOM into page and animate:
dom.hide();
$target_element.append(dom); // <-- append/prepend/replace whatever.
dom.show(); // <-- replace with custom animation
});

You can attach event handlers to the data that you get via the get() inside of the callback function. For example
$.get('content.inc.php', {id:id}, function(data){
$('#feature').children().fadeTo('fast', 0).parent().slideUp('slow', function(){
$(this).html(data).find('a').click(function(e) {
// specify an event handler for <a> elements in returned data
}).end().slideDown('slow');
});
});
live() may also be an option for you, depending on what events you want to bind to (since live() uses event delegation, not all events are supported).

Andy try this. It will call the Cufon code after each AJAX request is complete and before the html is actually added to the page.
$.get('content.inc.php', {id:id}, function(data){
$('#feature').children().fadeTo('fast', 0).parent().slideUp('slow', function(){
$(this).html(data);
Cufon.replace('h1');
$(this).slideDown('slow');
});
});

JavaScript is not executed because of a security reason OR beccause jQuery is just setting this element's innerHTML to some text (which is not interpreted as a JavScript) if it's contained. So the security is the beside effect.
How to solve it?
try to find all SCRIPT tags in Your response and execute them as fallows:
var scripts = myelement.getElementsByTagName("SCRIPT");
var i = 0;
for (i = 0; i < scripts.length; i++)
eval(scripts[i].innerHTML);