Forgive my naivety, this probably is quite obvious, I just can't see it now.
Please tell me what is wrong with the following code:
$('#iframe1').load(function(){
$('#iframe2').load(function(){
alert('loaded!');
});
});
The idea is to wait until both iframes have fully loaded, then alert "loaded" - of course this is a simplified example for the sake of stack.
The script sits in script tags at the end of the body of the html doc.
#Quertiy answer is perfectly fine, but not very jQuery-ish. It is hard-coded for 2 iframes only.
The beauty of jQuery is that you can make it work for the most number of people, with as little friction as possible.
I've advised a very simplistic plugin that does nearly what is present on that answer, but in a more open way. It not only works on iframes, but also on images, audio, video and whatever has a onload event!
Without further due, here's the code:
(function($){
$.fn.extend({allLoaded: function(fn){
if(!(fn instanceof Function))
{
throw new TypeError('fn must be a function');
}
var $elems = this;
var waiting = this.length;
var handler = function(){
--waiting;
if(!waiting)
{
setTimeout(fn.bind(window), 4);
}
};
return $elems.one('load.allLoaded', handler);
}});
})(window.jQuery);
It works by adding a load handler to every element in that selection. Since it is a plugin, you can use in whatever way you decide to use it.
Here's an example, that loads 30 random images:
//plugin code
(function($){
$.fn.extend({allLoaded: function(fn){
if(!(fn instanceof Function))
{
throw new TypeError('fn must be a function');
}
var $elems = this;
var waiting = this.length;
var handler = function(){
--waiting;
if(!waiting)
{
setTimeout(fn.bind(window), 4);
}
};
return $elems.one('load.allLoaded', handler);
}});
})(window.jQuery);
$(function(){
//generates the code for the 30 images
for(var i = 0, html = ''; i < 30; i++)
html += '<img data-src="http://lorempixel.com/g/400/200/?_=' + Math.random() + '">';
//stuffs the code into the body
$('#imgs').html(html);
//we select all images now
$('img')
.allLoaded(function(){
//runs when done
alert('loaded all')
})
.each(function(){
//the image URL is on a `data` attribute, to delay the loading
this.src = this.getAttribute('data-src')
})
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.0/jquery.min.js"></script>
<div id="imgs"></div>
Your problem, as said before many times, is that you have a load event attached to your iframe. That event is fired everytime the content change.
After that, you set a new event on #iframe2. When it's content changes, it will fire events left and right, above and beyound what you wish!
The best aproach is to keep track of which ones you loaded or not. After all have been loaded, you simply run the function.
The problem is that you're waiting until #iframe1 loads before you attach a handler for #iframe2 loading. So if #iframe2 loads first, you'll never get your callback.
Instead, watch the load event on both of them and track which ones you've seen:
var seen1 = false,
seen2 = false;
$('#iframe1, #iframe2').load(function(){
if (this.id == "iframe1") {
seen1 = true;
} else {
seen2 = true;
}
if (seen1 && seen2) {
alert('loaded!');
}
});
Why do you expect 2nd iframe to load after the first one?
~function () {
var loaded = 0;
$('#iframe1, #iframe2').load(function (){
if (++loaded === 2) {
alert('loaded!');
}
});
}()
Related
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 set event listeners but it's only working if I set them within setTimeout.
Doesn't work:
WebApp.setController('jobs', function() {
WebApp.setView('header', 'header');
WebApp.setView('nav', 'nav');
WebApp.setView('jobs', 'main');
var jobs = document.querySelectorAll('.jobs-category');
for(let i = 0; i < jobs.length; i++)
{
console.log('events added');
jobs[i].addEventListener("dragover", function( event ) {
console.log('drag over');
event.preventDefault();
});
jobs[i].addEventListener('drop', function(event) {
event.preventDefault();
console.log('dropped');
}, false);
}
});
Does work:
WebApp.setController('jobs', function() {
WebApp.setView('header', 'header');
WebApp.setView('nav', 'nav');
WebApp.setView('jobs', 'main');
window.setTimeout(function() {
var jobs = document.querySelectorAll('.jobs-category');
for(let i = 0; i < jobs.length; i++)
{
console.log('events added');
jobs[i].addEventListener("dragover", function( event ) {
console.log('drag over');
event.preventDefault();
});
jobs[i].addEventListener('drop', function(event) {
event.preventDefault();
console.log('dropped');
}, false);
}
}, 1);
});
(only setTimout is different/additionally)
setController() saves the function and executes it if the route get requested.
setView() binds HTML5-templates to DOM:
var Template = document.querySelector('#' + Name);
var Clone = document.importNode(Template.content, true);
var CloneElement = document.createElement('div');
CloneElement.appendChild(Clone);
CloneElement = this.replacePlaceholders(CloneElement);
document.querySelector(Element).innerHTML = CloneElement.innerHTML;
Why does this only work in setTimeout? I thought javascript is synchronous.
Addition: This is a single page app, which gets already loaded after DOM is ready.
Where is your Javascript within the page?
My guess is that the HTML is not ready yet when you try to register the event, this is why it only works with setTimeout.
Try either including your javascript at the bottom of the page (after the HTML) or listening to the page loaded event. See this question for info how to do that - $(document).ready equivalent without jQuery.
Per your assumption of synchronous javascript - yes it is (mostly) but also the way that the browser renders the page is (unless using async loading of scripts). Which means that HTML that is after a javascript will not be available yet.
UPDATE - per your comment of using a single page app, you must listen to the load complete/done/successful event. Another way you could bypass it will be listening to the events on the parent element (which is always there).
Hope this helps.
document.addEventListener("DOMContentLoaded", function(event) {
//do work
});
Most likely you are loading your JS file before your html content. You can't run your Javascript functions until the DOM is ready.
I'm trying to implement a simple image slider on my website but it doesn't seem to want to work. Nothing happens at all. Nothing I can think of has worked thus far so I thought I'd ask here. This is my code.
window.onload = function(){
image = document.getElementById("slideShow");
index = 0;
setInterval(slide, 3000);
};
function slide(){
index++;
if(index >= 6) {index = 0;}
path = "images/Slideshow/image"+index+".jpeg";
image.setAttribute("src",path);
}
window.onload is pretty cheesy because nobody seems to agree on what onload actually means.
i would recommend you use
document.addEventListener("DOMContentLoaded", function(){
// code
});
Another thing u should be aware of is slow loading. If the scripts gets loaded after the ready event has been fired then your code will never trigger.
A solution is wrapping the ready function is a seperate module.
var eventReady;
(function(){
var funcArr = [];
eventReady = function(func){
funcArr.push(func);
}
document.addEventListener("DOMContentLoaded", function(){
for(var i=0;i<funcArr.length;i++){
try{
funcArr[i]();
}
catch(e){
throw(e);
}
finally{
continue;
}
};
eventReady = function(func){
func();
}
});
})();
and then use the module like:
eventReady(function(){
// code
})
I'm desperate having spent well over an hour trying to troubleshoot this. I am trying to access a node in the DOM which is created from an ASP.NET control. I'm using exactly the same id and I can see that they match up when looking at the HTML source code after the page has rendered. Here's my [MODIFIED according to suggestions, but still not working] code:
ASP.NET Header
<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
<script type="text/javascript">
$(document).ready(
var el = document.getElementById('<%= txtBox.ClientID %>');
el.onchange = alert('test!!');
)
</script>
</asp:Content>
ASP.NET Body
<asp:TextBox ID="txtBox" runat="server"></asp:TextBox>
Resulting Javascript & HTML from above
<script type="text/javascript">
$(document).ready(
var el = document.getElementById('MainContent_txtBox');
el.onchange = alert('test!!');
)
</script>
...
<textarea name="ctl00$MainContent$txtBox" id="MainContent_txtBox"></textarea>
I can only assume that the script is loading before the control id has been resolved, yet when I look at the timeline with Chrome's "Inspect Element" feature, it appears that is not the case. When I created a regular textarea box to test and implement the identical code (different id of course), the alert box fires.
What on earth am I missing here? This is driving me crazy >.<
EDIT: Wierd code that works, but only on the initial page load; firing onload rather than onchange. Even jQuery says that .ready doesn't work properly apparently. Ugh!!
$(document).ready(function() {
document.getElementById('<%= txtBox.ClientID %>').onchange = alert('WORKING!');
})
Assuming the rendered markup does appear in that order, the problem is that the element doesn't yet exist at the time your JavaScript is attempting to locate it.
Either move that JS below the element (preferably right at the end of the body) or wrap it in something like jQuery's document ready event handler.
Update:
In response to your edits, you're almost there but (as others have mentioned) you need to assign a function to the onchange event, not the return result of alert(). Something like this:
$(document).ready(function() {
// Might as well use jQuery to attach the event since you're already using
// it for the document ready event.
$('#<%= txtBox.ClientID %>').change(function() {
alert('Working!');
});
});
By writing onchange = alert('Working');, you were asking JavaScript to assign the result of the alert() method to the onchange property. That's why it was executing it immediately on page load, but never actually in response to the onchange event (because you hadn't assigned that a function to run onchange).
Pick up jQuery.
Then you can
$(function()
{
var el = document.getElementById('<%= txtBox.ClientID %>');
el.onclick() { alert('test!!'); }
});
Other answers have pointed out the error (attempting to access DOM nodes before they are in the document), I'll just point out alternative solutions.
Simple method
Add the script element in the HTML below the closing tag of the element you wish to access. In its easiest form, put it just before the closing body tag. This strategy can also make the page appear faster as the browser doesn't pause loading HTML for script. Overall load time is the same however, scripts still have to be loaded an executed, it's just that this order makes it seem faseter to the user.
Use window.onload or <body onload="..." ...>
This method is supported by every browser, but it fires after all content is loaded so the page may appear inactive for a short time (or perhaps a long time if loading is dealyed). It is very robust though.
Use a DOM ready function
Others have suggested jQuery, but you may not want 4,000 lines and 90kb of code just for a DOM ready function. jQuery's is quite convoluted so hard to remove from the library. David Mark's MyLibrary however is very modular and quite easy to extract just the bits you want. The code quality is also excellent, at least the equal of any other library.
Here is an example of a DOM ready function extracted from MyLibrary:
var API = API || {};
(function(global) {
var doc = (typeof global.document == 'object')? global.document : null;
var attachDocumentReadyListener, bReady, documentReady,
documentReadyListener, readyListeners = [];
var canAddDocumentReadyListener, canAddWindowLoadListener,
canAttachWindowLoadListener;
if (doc) {
canAddDocumentReadyListener = !!doc.addEventListener;
canAddWindowLoadListener = !!global.addEventListener;
canAttachWindowLoadListener = !!global.attachEvent;
bReady = false;
documentReady = function() { return bReady; };
documentReadyListener = function(e) {
if (!bReady) {
bReady = true;
var i = readyListeners.length;
var m = i - 1;
// NOTE: e may be undefined (not always called by event handler)
while (i--) { readyListeners[m - i](e); }
}
};
attachDocumentReadyListener = function(fn, docNode) {
docNode = docNode || global.document;
if (docNode == global.document) {
if (!readyListeners.length) {
if (canAddDocumentReadyListener) {
docNode.addEventListener('DOMContentLoaded',
documentReadyListener, false);
}
if (canAddWindowLoadListener) {
global.addEventListener('load', documentReadyListener, false);
}
else if (canAttachWindowLoadListener) {
global.attachEvent('onload', documentReadyListener);
} else {
var oldOnLoad = global.onload;
global.onload = function(e) {
if (oldOnLoad) {
oldOnLoad(e);
}
documentReadyListener();
};
}
}
readyListeners[readyListeners.length] = fn;
return true;
}
// NOTE: no special handling for other documents
// It might be useful to add additional queues for frames/objects
else {
if (canAddDocumentReadyListener) {
docNode.addEventListener('DOMContentLoaded', fn, false);
return true;
}
return false;
}
};
API.documentReady = documentReady;
API.documentReadyListener = documentReadyListener;
API.attachDocumentReadyListener = attachDocumentReadyListener;
}
}(this));
Using it for your case:
function someFn() {
var el = document.getElementById('MainContent_txtBox');
el.onclick = function() { alert('test!!');
}
API.attachDocumentReadyListener(someFn);
or an anonymous function can be supplied:
API.attachDocumentReadyListener(function(){
var el = document.getElementById('MainContent_txtBox');
el.onclick = function() { alert('test!!');
};
Very simple DOM ready functions can be done in 10 lines of code if you just want one for a specific case, but of course they are less robust and not as reusable.
We are using jQuery thickbox to dynamically display an iframe when someone clicks on a picture. In this iframe, we are using galleria a javascript library to display multiple pictures.
The problem seems to be that $(document).ready in the iframe seems to be fired too soon and the iframe content isn't even loaded yet, so galleria code is not applied properly on the DOM elements. $(document).ready seems to use the iframe parent ready state to decide if the iframe is ready.
If we extract the function called by document ready in a separate function and call it after a timeout of 100 ms. It works, but we can't take the chance in production with a slow computer.
$(document).ready(function() { setTimeout(ApplyGalleria, 100); });
My question: which jQuery event should we bind to to be able to execute our code when the dynamic iframe is ready and not just it's a parent?
I answered a similar question (see Javascript callback when IFRAME is finished loading?).
You can obtain control over the iframe load event with the following code:
function callIframe(url, callback) {
$(document.body).append('<IFRAME id="myId" ...>');
$('iframe#myId').attr('src', url);
$('iframe#myId').load(function() {
callback(this);
});
}
In dealing with iframes I found good enough to use load event instead of document ready event.
Using jQuery 1.3.2 the following worked for me:
$('iframe').ready(function() {
$('body', $('iframe').contents()).html('Hello World!');
});
REVISION:!
Actually the above code sometimes looks like it works in Firefox, never looks like it works in Opera.
Instead I implemented a polling solution for my purposes. Simplified down it looks like this:
$(function() {
function manipIframe() {
el = $('body', $('iframe').contents());
if (el.length != 1) {
setTimeout(manipIframe, 100);
return;
}
el.html('Hello World!');
}
manipIframe();
});
This doesn't require code in the called iframe pages. All code resides and executes from the parent frame/window.
In IFrames I usually solve this problem by putting a small script to the very end of the block:
<body>
The content of your IFrame
<script type="text/javascript">
//<![CDATA[
fireOnReadyEvent();
parent.IFrameLoaded();
//]]>
</script>
</body>
This work most of the time for me. Sometimes the simplest and most naive solution is the most appropriate.
Following DrJokepu's and David Murdoch idea I implemented a more complete version.
It requires jQuery on both the parent and iframe and the iframe to be in your control.
iframe code:
var iframe = window.frameElement;
if (iframe){
iframe.contentDocument = document;//normalization: some browsers don't set the contentDocument, only the contentWindow
var parent = window.parent;
$(parent.document).ready(function(){//wait for parent to make sure it has jQuery ready
var parent$ = parent.jQuery;
parent$(iframe).trigger("iframeloading");
$(function(){
parent$(iframe).trigger("iframeready");
});
$(window).load(function(){//kind of unnecessary, but here for completion
parent$(iframe).trigger("iframeloaded");
});
$(window).unload(function(e){//not possible to prevent default
parent$(iframe).trigger("iframeunloaded");
});
$(window).on("beforeunload",function(){
parent$(iframe).trigger("iframebeforeunload");
});
});
}
parent test code:
$(function(){
$("iframe").on("iframeloading iframeready iframeloaded iframebeforeunload iframeunloaded", function(e){
console.log(e.type);
});
});
Found the solution to the problem.
When you click on a thickbox link that open a iframe, it insert an iframe with an id of TB_iframeContent.
Instead of relying on the $(document).ready event in the iframe code, I just have to bind to the load event of the iframe in the parent document:
$('#TB_iframeContent', top.document).load(ApplyGalleria);
This code is in the iframe but binds to an event of a control in the parent document. It works in FireFox and IE.
This function from this answer is the best way to handle this as $.ready explicitly fails for iframes. Here's the decision not to support this.
The load event also doesn't fire if the iframe has already loaded. Very frustrating that this remains a problem in 2020!
function onIframeReady($i, successFn, errorFn) {
try {
const iCon = $i.first()[0].contentWindow,
bl = "about:blank",
compl = "complete";
const callCallback = () => {
try {
const $con = $i.contents();
if($con.length === 0) { // https://git.io/vV8yU
throw new Error("iframe inaccessible");
}
successFn($con);
} catch(e) { // accessing contents failed
errorFn();
}
};
const observeOnload = () => {
$i.on("load.jqueryMark", () => {
try {
const src = $i.attr("src").trim(),
href = iCon.location.href;
if(href !== bl || src === bl || src === "") {
$i.off("load.jqueryMark");
callCallback();
}
} catch(e) {
errorFn();
}
});
};
if(iCon.document.readyState === compl) {
const src = $i.attr("src").trim(),
href = iCon.location.href;
if(href === bl && src !== bl && src !== "") {
observeOnload();
} else {
callCallback();
}
} else {
observeOnload();
}
} catch(e) {
errorFn();
}
}
Basically what others have already posted but IMHO a bit cleaner:
$('<iframe/>', {
src: 'https://example.com/',
load: function() {
alert("loaded")
}
}).appendTo('body');
Try this,
<iframe id="testframe" src="about:blank" onload="if (testframe.location.href != 'about:blank') testframe_loaded()"></iframe>
All you need to do then is create the JavaScript function testframe_loaded().
I'm loading the PDF with jQuery ajax into browser cache. Then I create embedded element with data already in browser cache. I guess it will work with iframe too.
var url = "http://example.com/my.pdf";
// show spinner
$.mobile.showPageLoadingMsg('b', note, false);
$.ajax({
url: url,
cache: true,
mimeType: 'application/pdf',
success: function () {
// display cached data
$(scroller).append('<embed type="application/pdf" src="' + url + '" />');
// hide spinner
$.mobile.hidePageLoadingMsg();
}
});
You have to set your http headers correctly as well.
HttpContext.Response.Expires = 1;
HttpContext.Response.Cache.SetNoServerCaching();
HttpContext.Response.Cache.SetAllowResponseInBrowserHistory(false);
HttpContext.Response.CacheControl = "Private";
This was the exact issue I ran into with our client. I created a little jquery plugin that seems to work for iframe readiness. It uses polling to check the iframe document readyState combined with the inner document url combined with the iframe source to make sure the iframe is in fact "ready".
The issue with "onload" is that you need access to the actual iframe being added to the DOM, if you don't then you need to try to catch the iframe loading which if it is cached then you may not. What I needed was a script that could be called anytime, and determine whether or not the iframe was "ready" or not.
Here's the question:
Holy grail for determining whether or not local iframe has loaded
and here's the jsfiddle I eventually came up with.
https://jsfiddle.net/q0smjkh5/10/
In the jsfiddle above, I am waiting for onload to append an iframe to the dom, then checking iframe's inner document's ready state - which should be cross domain because it's pointed to wikipedia - but Chrome seems to report "complete". The plug-in's iready method then gets called when the iframe is in fact ready. The callback tries to check the inner document's ready state again - this time reporting a cross domain request (which is correct) - anyway it seems to work for what I need and hope it helps others.
<script>
(function($, document, undefined) {
$.fn["iready"] = function(callback) {
var ifr = this.filter("iframe"),
arg = arguments,
src = this,
clc = null, // collection
lng = 50, // length of time to wait between intervals
ivl = -1, // interval id
chk = function(ifr) {
try {
var cnt = ifr.contents(),
doc = cnt[0],
src = ifr.attr("src"),
url = doc.URL;
switch (doc.readyState) {
case "complete":
if (!src || src === "about:blank") {
// we don't care about empty iframes
ifr.data("ready", "true");
} else if (!url || url === "about:blank") {
// empty document still needs loaded
ifr.data("ready", undefined);
} else {
// not an empty iframe and not an empty src
// should be loaded
ifr.data("ready", true);
}
break;
case "interactive":
ifr.data("ready", "true");
break;
case "loading":
default:
// still loading
break;
}
} catch (ignore) {
// as far as we're concerned the iframe is ready
// since we won't be able to access it cross domain
ifr.data("ready", "true");
}
return ifr.data("ready") === "true";
};
if (ifr.length) {
ifr.each(function() {
if (!$(this).data("ready")) {
// add to collection
clc = (clc) ? clc.add($(this)) : $(this);
}
});
if (clc) {
ivl = setInterval(function() {
var rd = true;
clc.each(function() {
if (!$(this).data("ready")) {
if (!chk($(this))) {
rd = false;
}
}
});
if (rd) {
clearInterval(ivl);
clc = null;
callback.apply(src, arg);
}
}, lng);
} else {
clc = null;
callback.apply(src, arg);
}
} else {
clc = null;
callback.apply(this, arguments);
}
return this;
};
}(jQuery, document));
</script>