in this small project I tried to play with window.load and $(document).ready()
https://jsfiddle.net/23rupa07/
What I read was that $(document).ready() is triggered immediately when DOM is loaded and window.load is waiting until for example images are loaded.
For jQuery version 2.2.4 it's working as is mentioned above, but when I change jQuery to version 3.1.0 the order is reverted.
Check screenshot. Does anyone know why?
document ready change between jQuery2 and jQuery3
One of the changes of jQuery 3 is that as of now - the document-ready handlers are asynchronous, even if the document is currently ready at the point where the handler is added. This provides a consistent code execution order that is independent of whether the document is ready or not[1].
This change required implementing a queue functionality for the document-ready callbacks, and this also affect other calls for events that are not called from the jQuery object.
If we take this code for example:
window.addEventListener('DOMContentLoaded', function() {
console.log('vanilla - DOMContentLoaded');
});
$(function(){
console.log('jquery - DOM loaded');
});
jQuery2 will give us:
jquery - DOM loaded
vanilla - DOMContentLoaded
jQuery3 will give us:
vanilla - DOMContentLoaded
jquery - DOM loaded
The behavior we see in the OP is related to a race-condition between the "fire" event of the document-ready's callbacks and the window.onload function.
This code will can show that the two functions run "at the same time", and it's only a matter of code-execution inside the VM of the browser:
$(function(){
console.log('jquery - DOM loaded')
});
window.onload = function(){
setTimeout(function() {
console.log('window - loaded');
}, 0);
}
<script type="text/javascript" src="//code.jquery.com/jquery-3.1.0.js"></script>
Regarding the question about the images - since the images are already in your cache when you load the document, it only seems like the window.onload function is called before the document.ready (it's a race condition), however if you will make sure the images will never cache - you will see that you get exactly the same results for both jquery2 and jquery3.
jQuery 2
$(document).ready(function(){
console.log('jquery - DOM loaded');
});
window.onload = function(){
console.log('window - loaded');
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.4/jquery.min.js"></script>
<script>
for (i = 0; i < 6; i++) {
document.writeln('<img src="https://o.aolcdn.com/commerce/autodata/images/USC60LGC051A021001.jpg?'+ parseInt(Math.random()*10000) +'" alt="">');
}
</script>
jQuery 3
$(document).ready(function(){
console.log('jquery - DOM loaded');
});
window.onload = function(){
console.log('window - loaded');
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.0/jquery.min.js"></script>
<script>
for (i = 0; i < 6; i++) {
document.writeln('<img src="https://o.aolcdn.com/commerce/autodata/images/USC60LGC051A021001.jpg?'+ parseInt(Math.random()*10000) +'" alt="">');
}
</script>
Related
I need to execute some JavaScript code when the page has fully loaded. This includes things like images.
I know you can check if the DOM is ready, but I don’t know if this is the same as when the page is fully loaded.
That's called load. It came waaaaay before DOM ready was around, and DOM ready was actually created for the exact reason that load waited on images.
window.addEventListener('load', function () {
alert("It's loaded!")
})
For completeness sake, you might also want to bind it to DOMContentLoaded, which is now widely supported
document.addEventListener("DOMContentLoaded", function(event){
// your code here
});
More info: https://developer.mozilla.org/en-US/docs/Web/Events/DOMContentLoaded
Usually you can use window.onload, but you may notice that recent browsers don't fire window.onload when you use the back/forward history buttons.
Some people suggest weird contortions to work around this problem, but really if you just make a window.onunload handler (even one that doesn't do anything), this caching behavior will be disabled in all browsers. The MDN documents this "feature" pretty well, but for some reason there are still people using setInterval and other weird hacks.
Some versions of Opera have a bug that can be worked around by adding the following somewhere in your page:
<script>history.navigationMode = 'compatible';</script>
If you're just trying to get a javascript function called once per-view (and not necessarily after the DOM is finished loading), you can do something like this:
<img src="javascript:location.href='javascript:yourFunction();';">
For example, I use this trick to preload a very large file into the cache on a loading screen:
<img src="bigfile"
onload="this.location.href='javascript:location.href=\'javascript:doredir();\';';doredir();">
Try this it Only Run After Entire Page Has Loaded
By Javascript
window.onload = function(){
// code goes here
};
By Jquery
$(window).bind("load", function() {
// code goes here
});
Try this code
document.onreadystatechange = function () {
if (document.readyState == "complete") {
initApplication();
}
}
visit https://developer.mozilla.org/en-US/docs/DOM/document.readyState for more details
Javascript using the onLoad() event, will wait for the page to be loaded before executing.
<body onload="somecode();" >
If you're using the jQuery framework's document ready function the code will load as soon as the DOM is loaded and before the page contents are loaded:
$(document).ready(function() {
// jQuery code goes here
});
the window.onload event will fire when everything is loaded, including images etc.
You would want to check the DOM ready status if you wanted your js code to execute as early as possible, but you still need to access DOM elements.
You may want to use window.onload, as the docs indicate that it's not fired until both the DOM is ready and ALL of the other assets in the page (images, etc.) are loaded.
In modern browsers with modern javascript (>= 2015) you can add type="module" to your script tag, and everything inside that script will execute after whole page loads. e.g:
<script type="module">
alert("runs after") // Whole page loads before this line execute
</script>
<script>
alert("runs before")
</script>
also older browsers will understand nomodule attribute. Something like this:
<script nomodule>
alert("tuns after")
</script>
For more information you can visit javascript.info.
And here's a way to do it with PrototypeJS:
Event.observe(window, 'load', function(event) {
// Do stuff
});
The onload property of the GlobalEventHandlers mixin is an event
handler for the load event of a Window, XMLHttpRequest, element,
etc., which fires when the resource has loaded.
So basically javascript already has onload method on window which get executed which page fully loaded including images...
You can do something:
var spinner = true;
window.onload = function() {
//whatever you like to do now, for example hide the spinner in this case
spinner = false;
};
Completing the answers from #Matchu and #abSiddique.
This:
window.addEventListener('load', (event) => {
console.log('page is fully loaded');
});
Is the same as this but using the onload event handler property:
window.onload = (event) => {
console.log('page is fully loaded');
};
Source:
https://developer.mozilla.org/en-US/docs/Web/API/Window/load_event
Live example here:
https://developer.mozilla.org/en-US/docs/Web/API/Window/load_event#live_example
If you need to use many onload use $(window).load instead (jQuery):
$(window).load(function() {
//code
});
2019 update: This is was the answer that worked for me. As I needed multiple ajax requests to fire and return data first to count the list items.
$(document).ajaxComplete(function(){
alert("Everything is ready now!");
});
I need to execute some JavaScript code when the page has fully loaded. This includes things like images.
I know you can check if the DOM is ready, but I don’t know if this is the same as when the page is fully loaded.
That's called load. It came waaaaay before DOM ready was around, and DOM ready was actually created for the exact reason that load waited on images.
window.addEventListener('load', function () {
alert("It's loaded!")
})
For completeness sake, you might also want to bind it to DOMContentLoaded, which is now widely supported
document.addEventListener("DOMContentLoaded", function(event){
// your code here
});
More info: https://developer.mozilla.org/en-US/docs/Web/Events/DOMContentLoaded
Usually you can use window.onload, but you may notice that recent browsers don't fire window.onload when you use the back/forward history buttons.
Some people suggest weird contortions to work around this problem, but really if you just make a window.onunload handler (even one that doesn't do anything), this caching behavior will be disabled in all browsers. The MDN documents this "feature" pretty well, but for some reason there are still people using setInterval and other weird hacks.
Some versions of Opera have a bug that can be worked around by adding the following somewhere in your page:
<script>history.navigationMode = 'compatible';</script>
If you're just trying to get a javascript function called once per-view (and not necessarily after the DOM is finished loading), you can do something like this:
<img src="javascript:location.href='javascript:yourFunction();';">
For example, I use this trick to preload a very large file into the cache on a loading screen:
<img src="bigfile"
onload="this.location.href='javascript:location.href=\'javascript:doredir();\';';doredir();">
Try this it Only Run After Entire Page Has Loaded
By Javascript
window.onload = function(){
// code goes here
};
By Jquery
$(window).bind("load", function() {
// code goes here
});
Try this code
document.onreadystatechange = function () {
if (document.readyState == "complete") {
initApplication();
}
}
visit https://developer.mozilla.org/en-US/docs/DOM/document.readyState for more details
Javascript using the onLoad() event, will wait for the page to be loaded before executing.
<body onload="somecode();" >
If you're using the jQuery framework's document ready function the code will load as soon as the DOM is loaded and before the page contents are loaded:
$(document).ready(function() {
// jQuery code goes here
});
the window.onload event will fire when everything is loaded, including images etc.
You would want to check the DOM ready status if you wanted your js code to execute as early as possible, but you still need to access DOM elements.
You may want to use window.onload, as the docs indicate that it's not fired until both the DOM is ready and ALL of the other assets in the page (images, etc.) are loaded.
In modern browsers with modern javascript (>= 2015) you can add type="module" to your script tag, and everything inside that script will execute after whole page loads. e.g:
<script type="module">
alert("runs after") // Whole page loads before this line execute
</script>
<script>
alert("runs before")
</script>
also older browsers will understand nomodule attribute. Something like this:
<script nomodule>
alert("tuns after")
</script>
For more information you can visit javascript.info.
And here's a way to do it with PrototypeJS:
Event.observe(window, 'load', function(event) {
// Do stuff
});
The onload property of the GlobalEventHandlers mixin is an event
handler for the load event of a Window, XMLHttpRequest, element,
etc., which fires when the resource has loaded.
So basically javascript already has onload method on window which get executed which page fully loaded including images...
You can do something:
var spinner = true;
window.onload = function() {
//whatever you like to do now, for example hide the spinner in this case
spinner = false;
};
Completing the answers from #Matchu and #abSiddique.
This:
window.addEventListener('load', (event) => {
console.log('page is fully loaded');
});
Is the same as this but using the onload event handler property:
window.onload = (event) => {
console.log('page is fully loaded');
};
Source:
https://developer.mozilla.org/en-US/docs/Web/API/Window/load_event
Live example here:
https://developer.mozilla.org/en-US/docs/Web/API/Window/load_event#live_example
If you need to use many onload use $(window).load instead (jQuery):
$(window).load(function() {
//code
});
2019 update: This is was the answer that worked for me. As I needed multiple ajax requests to fire and return data first to count the list items.
$(document).ajaxComplete(function(){
alert("Everything is ready now!");
});
At my website, I am loading jQuery asynchronously.
In order to do that, I must run jQuery functions only after it is really loaded.
I've tried two pure JS ways:
<script src="js/jquery-2.2.2.min.js" async></script>
<script>
window.addEventListener('load', function() {
//stuff
}, true);
</script>
And
window.onload = function() {
//stuff
}
But even so I still get Uncaught TypeError: $(...) is not a function at...
How do I fire jQuery functions after the lib is fully loaded?
You need to add the script only after jQuery library is loaded using script tag.
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script>
// your code should be here
alert(typeof jQuery)
</script>
The document ready handler is using to execute the code only after DOM elements are loaded.
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script>
console.log('Outside document ready handler ' + $('.test').length)
$(document).ready(function() {
console.log('Inside document ready handler ' + $('.test').length)
});
</script>
<div class="test"></div>
UPDATE 1: You can use defer if script is in a file, refer following question: jquery loaded async and ready function not working
UPDATE 2: Or you can bind load event handler to the script tag using addEventListener method.
<script async id="script" src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script type="text/javascript">
document.getElementById('script')
.addEventListener('load', function() {
alert(typeof jQuery)
});
</script>
FYI : I don't know why you are doing this, for optimizing the speed of content load it's always better to move the script tags at the end of body which helps to load content first.
You could do something like this:
function checkVariable(){
if ( window.jQuery){
Do your jquery stuff here
}
else{
window.setTimeout("checkVariable();",100);
}
}
checkVariable();
Apologies for the formatting...stuck on my phone right now.
I did not see this method listed, so I thought I would demonstrate using the JavaScript HTML DOM EventListener.
Example #1 Using the jQuery.ready() Method:
<p id="test-jquery">jQuery Not Loaded</p>
<script>
$(document).ready(function() {
var elem = $('#test-jquery');
elem.text('jQuery Is Loaded');
});
</script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
This method will not work since jQuery has yet to be loaded.
Running the above example will output:
ERROR: {
"message": "ReferenceError: $ is not defined",
"filename": "https://stacksnippets.net/js",
"lineno": 13,
"colno": 3
}
Example #2 Using the addEventListener() Method:
<p id="test-jquery">jQuery Not Loaded</p>
<script>
window.addEventListener('DOMContentLoaded', function() {
var elem = $('#test-jquery');
elem.text('jQuery Is Loaded');
});
</script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
This method will work since we are listening for the Window DOMContentLoaded event.
From Mozilla:
The original target for this event is the Document that has loaded.
You can listen for this event on the Window interface to handle it in
the capture or bubbling phases. For full details on this event please
see the page on the Document: DOMContentLoaded event.
A different event, load, should be used only to detect a fully-loaded
page. It is a common mistake to use load where DOMContentLoaded would
be more appropriate.
You can use this:
<script>
document.addEventListener('readystatechange', event => {
if (event.target.readyState === "complete") {
// window loaded, external resources are loaded too...
jQuery(function($) {
// your code here: $("a").css(...)
}
}
});
</script>
I used it when inline jQuery script did not work on safari (Mac and iOS) and this solved the problem.
Use document.ready or load the library in the header. That should work.. Be sure to load in the right folder or in the right link. If you are usying a link to load jquery then be sure to have an internet connection
I cannot wrap my head around this issue and the vast offer of information I found on the net:
On my project the JQuery is loaded with "defer". This I cannot change due to project standards.
<script defer src='https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.0/jquery.min.js'></script>
Now I need to add some small functions to a page (currently inline):
With this setup the browser will try to execute the inline scrip before jQuery loads => "Uncaught ReferenceError: $ is not defined"
<body>
...
...
<script>
$("#city").change(function() {...some stuff...};
$("#doctor").change(function() {...some stuff...};
</script>
</body>
Whats the smart way to resolve this?
Wrap it inside window.onload, so the script will only be executed when everything is fully loaded.
Try this example:
window.onload = function () {
$("#city").click(function() {
alert('city');
});
$("#doctor").click(function() {
alert('doctor');
});
}
<script defer src='https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.0/jquery.min.js'></script>
<button id="city">City</button>
<button id="doctor">Doctor</button>
Explanation about window.onload from MDN:
The load event fires at the end of the document loading process. At this point, all of the objects in the document are in the DOM, and all the images, scripts, links, and sub-frames have finished loading.
https://developer.mozilla.org/en/docs/Web/API/GlobalEventHandlers/onload
For more idiomatic (in jquery) way, use the code below. it's the same with window.onload.
$(document).ready(function() {
// put code here
});
Another alternative, use $(function() { }).
$(function() {
// put code here
})
Pros: With this approach, you don't have to wait for the 'load' event to trigger.. this should execute as soon as jQuery has finished loading.
var initInterval = setInterval(function(){
if(window.jQuery) {
clearInterval(initInterval);
init(); // where init is the entry point for your code execution
}
}, 20);
function init(){
$('#example').text('Ahoy!');
}
<script defer src='https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.0/jquery.min.js'></script>
<div id="example">Hi</div>
This way you can add multiple functions to window.load:
window.addEventListener("load",function(event) {
$("#city").click(function() {
alert('city');
});
},false);
window.addEventListener("load",function(){
$("#doctor").click(function() {
alert('doctor');
});
},false);
Is there anyway to check if page is fully loaded.Something like this http://msdn.microsoft.com/en-us/library/system.web.ui.page.loadcomplete.aspx but for JAVA.
If you intend to execute logic on the client side when the page is loaded, you might be interested in the Javascript onload event.
Or, even better, consider using jQuery and use the ready() function to execute your logic.
Just a short example using jQuery:
$(document).ready(function() {
alert("The document, including all assets such as images, has been completely received");
});
Not directly in java, since it is probably not running in the browser, but you can do it with javascript
<html>
<head>
<title>Test Page</title>
<script type="text/javascript">var myFunc = function() {
alert("The page is fully loaded!");
};
window.onload = myFunc;
</script>
</head>
you can use the normal onload()
<body onload="yourFunctionHere()">
or the JQuery version
$(document).ready(function() {
yourFunctionHere();
});
1. JQuery will help you:
there is $(document).ready() which tell you that the browser is loaded.
Example:
$(document).ready(function(){
$("button").click(function(){
$("p").slideToggle();
});
});
The ready event occurs when the DOM (document object model) has been loaded, and the page has been fully loaded (including images).
Because this event occurs after the document is ready, it is a good place to have all other jQuery events and functions. Like in the example above.
2.Window onload is another JavaScript approach:
window.onload=function(){SomeJavaScriptCode};
The onload event occurs when an object has been loaded.
onload is most often used within the element to execute a script once a web page has completely loaded all content (including images, script files, CSS files, etc.).
Note: The main difference is that document.ready() event gets called as soon as your DOM is loaded. It does not wait for the contents to get loaded fully, while window.onload will wait until all your contents are loaded fully.
We can have more than one document.ready() function in a page where we can have only one onload function.
Not in Java, no.
You'll need Javascript:
<script>
window.onload = function() {
alert('Loading Complete!');
}
</script>