I am lazy loading my Facebook comments plugin, but the plugin takes a while to load. I want the user to know that it's loading by adding a loading GIF. I know how to add the loading GIF, but I don't know how to remove it once the comments plugin has loaded fully. This is what I've tried:
<img id="loading" src="/media/assets/loading.gif">
<script>
function loadAPI() {
var js = document.createElement('script');
js.src = "//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.5";
document.body.appendChild(js);
js.onload=loading();
}
window.onscroll = function () {
var rect = document.getElementById('comments').getBoundingClientRect();
if (rect.top < window.innerHeight) {
loadAPI();
window.onscroll = null;
}
}
//Function used to remove GIF
function loading(){
var loading = document.getElementById('loading');
loading .parentNode.removeChild(loading);
}
</script>
<div id="fb-root"></div>
<div id="comments" class="fb-comments" data-href="http://example.com" data-numposts="5" data-colorscheme="light"></div>
The code I am using, displays the GIF when the user scrolls to the comments section part, and then removes it after all the functions have been invoked. This is not what I want. I want it to get removed after the Faceboook Comments plugin has been displayed. My code removes the GIF a good bit of time prior the plugin displaying. What can I do to fix this issue?
First of all, you are invoking the loading function when you'd actually need to pass the reference to js.onload, so the loading callback gets executed before the Facebook plugin has even finished loading the javascript.
So, change
js.onload=loading();
to
js.onload=loading;
Now the gif gets removed when the plugin itself has finished loading, but we can do better than that. The plugin will set a global object FB which you can use to subscribe to the render event of the comments (source), like so:
FB.Event.subscribe("xfbml.render", function(){
//The comments are now rendered, remove the image
});
Putting it all together:
<img id="loading" src="/media/assets/loading.gif">
<script>
function loadAPI() {
var js = document.createElement('script');
js.src = "//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.5";
document.body.appendChild(js);
js.onload=loading;
}
window.onscroll = function () {
var rect = document.getElementById('comments').getBoundingClientRect();
if (rect.top < window.innerHeight) {
loadAPI();
window.onscroll = null;
}
}
//Function used to remove GIF
function loading(){
FB.Event.subscribe('xfbml.render', function(){
var loading = document.getElementById('loading');
loading.parentNode.removeChild(loading);
});
}
</script>
<div id="fb-root"></div>
Related
I do update a html fragment via htmx.
How to load a JS library which is needed for this new snippet?
How to execute a function after the snippet got loaded?
Example:
I want to show an joyful animation (confetti) after the html snippet got added to the page.
This means the browser needs to load this:
<script src="https://cdn.jsdelivr.net/npm/canvas-confetti#1.4.0/dist/confetti.browser.min.js"></script>
After loading above lib a JS function needs to get executed.
How to do this with htmx?
I found a solution. I guess it could get improved. Please leave a comment if you know a simpler way.
// lala.js
// this file gets loaded in the page (before the hx-post call)
function loadScript(url, callback) {
// https://stackoverflow.com/a/950146/633961
// Adding the script tag to the head as suggested before
var head = document.head;
var script = document.createElement('script');
script.type = 'text/javascript';
script.src = url;
// Then bind the event to the callback function.
// There are several events for cross browser compatibility.
script.onreadystatechange = callback;
script.onload = callback;
// Fire the loading
head.appendChild(script);
};
document.body.addEventListener("confetti", function(evt){
var target = document.getElementsByClassName('htmx-settling')[0];
loadScript('https://cdn.jsdelivr.net/npm/canvas-confetti#1.4.0/dist/confetti.browser.min.js',
function () {
var myCanvas = document.createElement('canvas');
var rect = target.getBoundingClientRect();
myCanvas.setAttribute('style', 'position: absolute; top:' +
rect.top + 'px; left:' + rect.left + 'px');
target.appendChild(myCanvas);
var myConfetti = confetti.create(myCanvas, {
resize: true,
useWorker: true
});
myConfetti({
particleCount: 100,
spread: 160
// any other options from the global
// confetti function
})
})
})
On the server side I return the response like this (Django):
def confetti_hx(request):
...
response = HttpResponse(html)
response['HX-Trigger-After-Swap'] = 'confetti'
return response
Right now there is no way to load a new library on a page built in to htmx (this is a necessary feature IMO, please log an issue for it) so the confetti library should be included initially as part of your main site.
After you have included the external library in the main website, you can include a normal script tag that executes the confetti code necessary inline:
<script>
var myCanvas = document.createElement('canvas');
document.appendChild(myCanvas);
var myConfetti = confetti.create(myCanvas, {
resize: true,
useWorker: true
});
myConfetti({
particleCount: 100,
spread: 160
// any other options from the global
// confetti function
});
</script>
What I've been doing is use some Hyperscript to do something like this:
<script
src="https://cdn.jsdelivr.net/npm/canvas-confetti#1.4.0/dist/confetti.browser.min.js"
_="
on load
js
<enter code here>
end
end
"
></script>
i have a link in my main page that uses ajax to retrieve a PDF which is displayed in an Iframe, i am trying to detect scroll event of the PDF document and display a message or do something. i have tried different solutions from other solutions on stackoverflow and google search in general and couldn't find a good solution.
Main.php
<html>
<!--ajax request-->
<script type="text/javascript">
$(document).on('click','#nextpdf',function(event) {
event.preventDefault();
var reg = $(this).attr("href");
var str = reg.split('?')[1];
$.ajax({
type: "GET",
url: '../functions/pdfreader.php',
data: 'pdfxs='+str+'',
cache:false,
async: false,
success: function(data) {
// data is ur summary
$('.refresh').html(data);
return false;
}
});//end of ajax
});
</script>
<?php
while($obj = $c_content->fetch())
{
$title = $obj['lecture_title'];
echo '<article class="comment2">
//pdf link
<div class="comment2-body">
<div class="text" style="color:#999;padding-right:130px;">
<p><a href="../functions/pdfreader.php?'.$title.'""
style="color:#999" id="nextpdf">'.$title.'</a></p>
</div>
</div>
</article>
';
}
?>
</html>
pdfreader.php
//detect iframe pdf scroll
<script type="text/javascript">
$("myiframe").load(function () {
var iframe = $("myiframe").contents();
$(iframe).scroll(function () {
alert('scrolling...');
});
});
</script>
<?php
........
while($obj = $gettrend->fetch())
{
$coursefile = $obj['lecture_content'];
//this is my iframe
echo '<div class="mov_pdf_frame"><iframe id="myiframe"
src="https://localhost/einstower/e-learn/courses/pdf/'.$coursefile.'"
id="pdf_content"
width="700px" height="800px" type="application/pdf">
</iframe></div>';
}
?>
The major problem here is that nothing happens when i scroll the pdf document, how can i detect scrolling?
i found this fiddle that works but i cant view the javascript solution. http://fiddle.jshell.net/czw8pbvj/1/
First off, $("myiframe") isn't finding anything, so it attaches a load event to nothing. 1) change it to $("#myiframe") or $("iframe").
Here's a working fiddle (for iframe scroll detection)
UPDATE: to detect the scroll within PDF document, you can't use iframe. For that, you need embed or object tags AND a JS-enabled PDF document (hopefully its your PDFs..), who can send messages to your page's JS (see this answer).
Unfortunately, I couldn't find a scroll event in Adobe's Acrobat API Reference. It lists only these events:
Event type: Event names
App: Init
Batch: Exec
Bookmark: Mouse Up
Console: Exec
Doc: DidPrint, DidSave, Open, WillClose, WillPrint, WillSave
External: Exec
Field: Blur, Calculate, Focus, Format, Keystroke, Mouse Down, Mouse Enter, Mouse Exit, Mouse Up, Validate
Link: Mouse Up
Menu: Exec
Page: Open, Close
Screen: InView, OutView, Open, Close, Focus, Blur, Mouse Up, Mouse Down, Mouse Enter, Mouse Exit
So, basically, I think what you want just isn't possible as for now, at least with default rendering. With custom rendering (https://github.com/mozilla/pdf.js) it could be possible, though I'm not sure.
Apparently, it could be done with page scroll (see this issue). So back to iframes solution. :^D
Because this question is asked a long time ago, i think i need to help with my experience before.
The answer is: You can not
Why? because PDF is rendered by external apps, such as adobe pdf reader, foxit or else. And you can not attach event on them.
if you are using adobe reader, The only you can do is goto page, change zoom etc. Full example you can read here: https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/pdf_open_parameters.pdf#page=8 (see. i bring you to page 8 directly instead to first page).
But, hei.. how if our client using another apps? we will confused more
The way to do this is only build your own pdf viewer.
we can using js library, like: http://www.bestjquery.com/2012/09/best-jquery-pdf-viewer-plugin-examples/
but here i only will show you to use pdf.js which created by mozilla.
main.php
<style>
.preview{
display:none;
width: 400px;
height: 400px;
border: 1px solid black;
}
</style>
file/test.pdf<br>
file/test1.pdf<br>
<div class="preview">
<iframe id="myiframe" frameborder="0" width="400px" height="400px" >not support iframe</iframe>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script type="text/javascript">
$(function(){
$(document).on('click', '#nextpdf', function(e){
e.preventDefault();
$('#myiframe').attr('src', $(this).attr('href'));
$('.preview').show();
});
//handle iframe on scroll
$('#myiframe').on('load', function () {
$(this).contents().scroll(function () {
console.log('scrolled');
}).click(function(){
console.log('clicked');
});
});
});
</script>
pdfreader.php
<?php
$path = 'file/';
$pdf = isset($_GET['pdfxs']) ? $path . $_GET['pdfxs'] : '';
if(!file_exists($pdf) || !mime_content_type($pdf) =='application/pdf') die('file not found');
?>
<div id="pdf-container">
<div id="pdf-box"></div>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="//mozilla.github.io/pdf.js/build/pdf.js"></script>
<script>
$(function(){
//original script : https://gist.github.com/fcingolani/3300351
function renderPDF(url, canvasContainer, options) {
var options = options || { scale: 1 };
function renderPage(page) {
var viewport = page.getViewport(options.scale);
var canvas = $(document.createElement('canvas'));
var renderContext = {
canvasContext: canvas[0].getContext('2d'),
viewport: viewport
};
canvas.attr('width', viewport.width).attr('height', viewport.height);
canvasContainer.append(canvas);
page.render(renderContext);
}
function renderPages(pdfDoc) {
for(var num = 1; num <= pdfDoc.numPages; num++)
pdfDoc.getPage(num).then(renderPage);
}
PDFJS.disableWorker = true;
PDFJS.getDocument(url).then(renderPages);
}
renderPDF('<?=$pdf;?>', $('#pdf-box'));
});
</script>
Note: i put pdf on folder file/
in main.php you will notice that you can attach event scroll (and click too) to the pdf. because our pdf is not rendered by external apps now.
and the last part is, if you read pdfreader.php carefully, you will notice that you no need iframe anymore. You just need div, and then you can fully handle all event that do you want to your pdf : like scroll, click, change page, zoom, etc. why?? because your pdf is redered as canvas now (pdf.js render your pdf as HTML5 canvas). see full example of pdf.js
Please try this
iframe.on( "scroll", handler )
$("#frame").scroll(function () {
if ($(window).scrollTop() == $(document).height() - $(window).height())
alert('Bottom reached');
});
I found this in the JSFiddle that was referenced in the Fiddle you linked. The HTML field is empty. This CSS was in there, too.
body {
height: 1500px;
}
In the fiddle that you linked, the <iframe> has an ID of frame. I figured you can use the jQuery selector like $("#frame").
I think this will help you.
$("#myiframe").load(function () {
$(this).contents().scroll(function () {
//your code here
});
});
I know there is a lot of these on Stackoverflow but I haven't found one that works for me in a recent version of jquery (1.10.2).
I did try:
$(".lazy").load(function (){}
But I believe after some research using .load to detect image load is deprecated in jQuery 1.8. What I need to do is fire an image resize function once the images are loaded. I don't have control over the
HTML and at the moment I am having to add the image dimensions via jQuery by attaching an attribute (via .attr()) once page loads so that I can use lazyload js.
The problem is that I need an accurate way to hold off all my various scripts until the image has loaded properly else the functions sometimes fire before every image had loaded. I have tried using $(window).load(function (){}); however it sometimes still fires before every image had loaded.
I usually do this:
var image = new Image();
image.onload = function () {
console.info("Image loaded !");
//do something...
}
image.onerror = function () {
console.error("Cannot load image");
//do something else...
}
image.src = "/images/blah/foo.jpg";
Remember that the loading is asynchronous so you have to continue the script inside the onload and onerror events.
There's also a useful .complete property of an image object, you can use it if you have already set the .src of your <img> before attaching to it any event listeners:
var img=document.getElementById('myimg');
var func=function(){
// do your code here
// `this` refers to the img object
};
if(img.complete){
func.call(img);
}
else{
img.onload=func;
}
Reference: http://www.w3schools.com/jsref/prop_img_complete.asp
I would give the images that require this constraint a class like mustLoad where:
<img class="mustLoad" src="..." alt="" />
and then create a generic image load handler function, such as:
$('img.mustLoad').on('load',function(){
/* Fire your image resize code here */
});
Edit:
In response to your comments about deprecating .load() above, .load() was deprecated, in favor of .on('load') to reduce ambiguity between the onLoad event and Ajax loading.
In the case of waiting of loading multiple images:
var images = $("#div-with-images img");
var unloaded = images.length;
images.on('load', function(){
-- unloaded;
if (!unloaded) {
// here all images loaded, do your stuff
}
});
What I need to do is fire an image resize function once the images are loaded.
Are you sure that you need the image to be loaded? Waiting for an image to load before resizing it can cause a large jump in the page layout, especially if the images have large file sizes, such as animated GIFs.
Usually, for an image resize, you only need to know the intrinsic dimensions of the image. While there is no event to tell you this, it's easy enough to poll the images for the data. Something like this could be particularly effective:
<img src="..." data-resizeme="123" />
(function() {
var images, l, i, tmp;
if( document.querySelectorAll) {
images = [].slice.call(document.querySelectorAll("img[data-resizeme]"),0);
}
else {
tmp = document.getElementsByTagName("img");
images = [];
// browser compatibility is fun!
for( i=tmp.length-1; i>=0; i--) {
if( tmp[i].getAttribute("data-resizeme")) images.unshift(tmp[i]);
}
}
for( i=images.length-1; i>=0; i--) {
images[i].onload = resizeImage;
images[i].onerror = cancelImageResize;
}
var timer = setInterval(function() {
for( i=images.length-1; i>=0; i--) {
if( images[i].width) {
resizeImage.call(images[i]);
images[i].onload = null;
cancelImageResize.call(images[i]);
}
}
if( images.length == 0) clearInterval(timer);
},100); // adjust granularity as needed - lower number is more responsive.
function cancelImageResize() {
var i;
for( i=images.length-1; i>=0; i--) {
if( images[i] == this) {
images.splice(i,1);
break;
}
}
}
function resizeImage() {
console.log("Image "+this.src+" is "+this.width+"x"+this.height);
}
})();
Hope this helps!
I want to add an image by Javascript, then calculating the html element width as
window.onload=function(){
document.getElementById('x').addEventListener('click', function(e){
var el = document.getElementById('xx');
el.innerHTML = '<img src="img.jpg" />';
var width = el.offsetWidth;
.....
}, false);
}
but since JavaScript conduct all processes simultaneously, I will get the width of the element before loading the image. How can I make sure that the image has been loaded into the content; then calculating the element width?
UPDATE: Thanks for the answers, but I think there is a misunderstanding. img src="img.jpg" /> does not exist in the DOM document. It will be added later by Javascript. Then, when trying to catch the element by Id, it is not there probably.
You can give the img an ID and do the following :-
var heavyImage = document.getElementById("my-img");//assuming your img ID is my-img
heavyImage.onload = function(){
//your code after image is fully loaded
}
window.onload=function(){
document.getElementById('x').addEventListener('click', function(e){
var el = document.getElementById('xx');
var img = new Image();//dynamically create image
img.src = "img.jpg";//set the src
img.alt = "alt";
el.appendChild(img);//append the image to the el
img.onload = function(){
var width = el.offsetWidth;
}
}, false);
}
This is untested, but if you add the image to the DOM, set an onload/load event-handler and then assign the src of the image, the event-handling should fire (once it's loaded) and allow you to find the width.
This is imperfect, though, since if the image is loaded from the browser's cache the onload/load event may not fire at all (particularly in Chromium/Chrome, I believe, though this is from memory of a bug that may, or may not, have since been fixed).
For the chrome bug you can use the following:-
var BLANK = 'data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///ywAAAAAAQABAAACAUwAOw==';//create a blank source
var tImg = document.getElementById("my-img");//get the image
var origSrc = tImg.src;//get the original src
tImg.src = BLANK;//change the img src to blank.
tImg.src = origSrc;//Change it back to original src. This will lead the chrome to load the image again.
tImg.onload= function(){
//your code after the image load
}
You can use a library called PreloadJS or you can try something like this:
//Somewhere in your document loading:
loadImage(yourImage, callbackOnComplete);
function loadImage(image, callbackOnComplete){
var self = this;
if(!image.complete)
window.content.setTimeout(
function() { self.loadImage(image, callbackOnComplete)}
,1000);
else callbackOnComplete();
}
I did this when I worked with images base64 which delay on loading.
I'm using jquery.load to pull in a fragment of html from another page. The fragment contains quite a large background image. Once the load function has finished and it calls it's callback I set the fragment to display block in the page - problem is that as the html loads I see the new content without the background image....the background image loads later.
Whats a good method of making sure the image is loaded before I show the ajax content?
You could do this...
$('button').click(function() {
$('#element').load('/echo/html/', function(responseText) {
// For testing
responseText = '<link href="http://sstatic.net/stackoverflow/all.css?v=ded66dc6482e" rel="stylesheet" type="text/css" /><div class="ac_loading" style="width: 200px; height: 200px;">ABC</div>';
var element = $(this),
responseTemp = $('<div />').hide().html(responseText).appendTo('body'),
styles = responseTemp.find('link[type="text/css"]'),
stylesHook = $('head link[type="text/css"]:last');
if (stylesHook.length === 0) {
stylesHook = $('head *:last-child');
}
styles.insertAfter(stylesHook);
preloadSrc = responseTemp.find('div').css('backgroundImage').replace(/^url\(["']?(.*?)["']?\)$/, '$1'), image = new Image();
image.onload = function() {
styles.add(responseTemp).remove();
element.html(responseText);
}
image.src = preloadSrc;
});
});
jsFiddle.