In this example someone shows a jQuery onclick event.
My shows this:
$(function() {
$('.post').on('click', function() {
SOME STUFF
});
});
But what are the first and last line doing?
if i remove the lines, it's not working:
$('.post').on('click', function() {
SOME STUFF
});
But why? In the linked example is a second commenter. He shows this way (without first/last line).
Can someone explain this?
It is a shortcut for $( document ).ready(...)
See http://api.jquery.com/ready/
Quoting the doc :
While JavaScript provides the load event for executing code when a page is rendered, this event does not get triggered until all assets such as images have been completely received. In most cases, the script can be run as soon as the DOM hierarchy has been fully constructed. The handler passed to .ready() is guaranteed to be executed after the DOM is ready, so this is usually the best place to attach all other event handlers and run other jQuery code. [...]
All three of the following syntaxes are equivalent:
* $( document ).ready( handler )
* $().ready( handler ) (this is not recommended)
* $( handler )
That is short for document.ready. It waits until the entire document is loaded and the element with class .post can be found and bound to.
If you omit that part, the jQuery function will not find the element and your event will not work.
The first and last lines create an anonymous function. In computer programming, an anonymous function is a function defined, and possibly called, without being bound to an identifier.
In the example here it is used to set the event listener that is loaded onload of the page.
$(function() {
$('.something').on('click', function() {
alert('hello');
$(this).addClass('classOne');
});
});
$(function(){});
is jQuery short hand for
$(document).ready(function() {});
which ensures your document is ready for manipulation before executing anything within it. In many ways its similar to the browser window.onready event. See jQuery docs..
The risk if you don't wrap your jQuery code in either of these forms of the functions is that you will try and manipulate elements before they have been created by the browser. Your code is not guaranteed to fail, but you could, at the very least, get inconsistent behaviour.
Related
What are differences between
$(document).ready(function(){
//my code here
});
and
$(window).load(function(){
//my code here
});
And I want to make sure that:
$(document).ready(function(){
})
and
$(function(){
});
and
jQuery(document).ready(function(){
});
are the same.
Can you tell me what differences and similarities between them?
$(document).ready(function() {
// executes when HTML-Document is loaded and DOM is ready
console.log("document is ready");
});
$(window).load(function() {
// executes when complete page is fully loaded, including all frames, objects and images
console.log("window is loaded");
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
Query 3.0 version
Breaking change: .load(), .unload(), and .error() removed
These methods are shortcuts for event operations, but had several API
limitations. The event .load() method conflicted with the ajax .load()
method. The .error() method could not be used with window.onerror
because of the way the DOM method is defined. If you need to attach
events by these names, use the .on() method, e.g. change
$("img").load(fn) to $(img).on("load", fn).1
$(window).load(function() {});
Should be changed to
$(window).on('load', function (e) {})
These are all equivalent:
$(function(){
});
jQuery(document).ready(function(){
});
$(document).ready(function(){
});
$(document).on('ready', function(){
})
document.ready is a jQuery event, it runs when the DOM is ready, e.g. all elements are there to be found/used, but not necessarily all the content.
window.onload fires later (or at the same time in the worst/failing cases) when images and such are loaded. So, if you're using image dimensions for example, you often want to use this instead.
Also read a related question:
Difference between $(window).load() and $(document).ready() functions
These three functions are the same:
$(document).ready(function(){
})
and
$(function(){
});
and
jQuery(document).ready(function(){
});
here $ is used for define jQuery like $ = jQuery.
Now difference is that
$(document).ready is jQuery event that is fired when DOM is loaded, so it’s fired when the document structure is ready.
$(window).load event is fired after whole content is loaded like page contain images,css etc.
From the jQuery API Document
While JavaScript provides the load event for executing code when a
page is rendered, this event does not get triggered until all assets
such as images have been completely received. In most cases, the
script can be run as soon as the DOM hierarchy has been fully
constructed. The handler passed to .ready() is guaranteed to be
executed after the DOM is ready, so this is usually the best place to
attach all other event handlers and run other jQuery code. When using
scripts that rely on the value of CSS style properties, it's important
to reference external stylesheets or embed style elements before
referencing the scripts.
In cases where code relies on loaded assets (for example, if the
dimensions of an image are required), the code should be placed in a
handler for the load event instead.
Answer to the second question -
No, they are identical as long as you are not using jQuery in no conflict mode.
The Difference between $(document).ready() and $(window).load() functions is that the code included inside $(window).load() will run once the entire page(images, iframes, stylesheets,etc) are loaded whereas the document ready event fires before all images,iframes etc. are loaded, but after the whole DOM itself is ready.
$(document).ready(function(){
})
and
$(function(){
});
and
jQuery(document).ready(function(){
});
There are not difference between the above 3 codes.
They are equivalent,but you may face conflict if any other JavaScript Frameworks uses the same dollar symbol $ as a shortcut name.
jQuery.noConflict();
jQuery.ready(function($){
//Code using $ as alias to jQuery
});
$(document).ready(function(e) {
// executes when HTML-Document is loaded and DOM is ready
console.log("page is loading now");
});
$(document).load(function(e) {
//when html page complete loaded
console.log("completely loaded");
});
The ready event is always execute at the only html page is loaded to the browser and the functions are executed....
But the load event is executed at the time of all the page contents are loaded to the browser for the page.....
we can use $ or jQuery when we use the noconflict() method in jquery scripts...
$(window).load is an event that fires when the DOM and all the content (everything) on the page is fully loaded like CSS, images and frames. One best example is if we want to get the actual image size or to get the details of anything we use it.
$(document).ready() indicates that code in it need to be executed once the DOM got loaded and ready to be manipulated by script. It won't wait for the images to load for executing the jQuery script.
<script type = "text/javascript">
//$(window).load was deprecated in 1.8, and removed in jquery 3.0
// $(window).load(function() {
// alert("$(window).load fired");
// });
$(document).ready(function() {
alert("$(document).ready fired");
});
</script>
$(window).load fired after the $(document).ready().
$(document).ready(function(){
})
//and
$(function(){
});
//and
jQuery(document).ready(function(){
});
Above 3 are same, $ is the alias name of jQuery, you may face conflict if any other JavaScript Frameworks uses the same dollar symbol $. If u face conflict jQuery team provide a solution no-conflict read more.
$(window).load was deprecated in 1.8, and removed in jquery 3.0
Yesterday I had an issue where a .on('click') event handler I was assigning wasn't working right. Turns out it's because I was was trying to apply that .on('click') before that element existed in the DOM, because it was being loaded via AJAX, and therefore didn't exist yet when the document.ready() got to that point.
I solved it with an awkward workaround, but my question is, if I were to put a <script> tag IN the ajax loaded content and another document.ready() within that, would that second document.ready() be parsed ONLY once that ajax content is done being loaded? In other words, does it consider that separately loaded ajax content to be another document, and if so, does having another document.ready() within that ajax-loaded HTML work the way I think it does?
Alternatively; what would be a better way to handle this situation? (needing to attach an event listener to a DOM element that doesn't yet exist on document.ready())
To answer your question: No, document.ready will not fire again once a ajax request is completed. (The content in the ajax is loaded into your document, so there isn't a second document for the ajax content).
To solve your problem just add the event listener to the Element where you load the ajax content into it.
For example:
$( "div.ajaxcontent-container" ).on( "click", "#id-of-the-element-in-the-ajax-content", function() {
console.log($( this ));
});
For #id-of-the-element-in-the-ajax-content you can use any selector you would use in $("selector"). The only difference is, only elements under div.ajaxcontent-container will be selected.
How it works:
As long as div.ajaxcontent-container exists all elements (if they exist now or only in the future) that match the selector #id-of-the-element-in-the-ajax-content will trigger this click-event.
Javascript in the resulting ajax call will not be excecuted (by default) due to safety. Also, you can't directly bind event to non-existing elements.
You can bind an event to some parent that does exist, and tell it to check it's children:
$(document).ready(function(){
$(document).on('eventName', '#nonExistingElement', function(){ alert(1); }
// or:
$('#existingParent').on('eventName', '#nonExistingElement', function(){ alert(1); }
});
Always try to get as close to the triggering element as you can, this will prevent unnessesary bubbling through the DOM
If you have some weird functions going on, you could do something like this:
function bindAllDocReadyThings(){
$('#nonExistingElement').off().on('eventName', function(){ alert(1); }
// Note the .off() this time, it removes all other events to set them again
}
$(document).ready(function(){
bindAllDocReadyThings();
});
$.ajaxComplete(function(){
bindAllDocReadyThings();
});
try this, that is not working because your control is not yet created and you are trying to attach a event, if you use on event it will work fine. let me know if you face any issues.
$(document).ready(function(){
$(document).on('click', '#element', function (evt) {
alert($(this).val());
});
});
The answer here is a delegated event:
JSFiddle
JSFiddle - Truly dynamic
jQuery
$(document).ready(function(){
// Listen for a button within .container to get clicked because .container is not dynamic
$('.container').on('click', 'input[type="button"]', function(){
alert($(this).val());
});
// we bound the click listener to .container child elements so any buttons inside of it get noticed
$('.container').append('<input type="button" class="dynamically_added" value="button2">');
$('.container').append('<input type="button" class="dynamically_added" value="button3">');
$('.container').append('<input type="button" class="dynamically_added" value="button4">');
$('.container').append('<input type="button" class="dynamically_added" value="button5">');
});
HTML
<div class="container">
<input type="button" class="dynamically_added" value="button1">
</div>
I'm working on a code-base with a friend that has a similar requirement. The delegated event handler option is definitely best if all you want is to attach event handlers. An alternative, especially if you need to do other DOM processing in your $(document).ready function, is to put the code you want run into a script element at the end of your code. Basically, instead of:
<script type="text/javascript">
$(document).ready(function() {
// Your code here
});
</script>
<!-- rest of dynamically loaded HTML -->
Try swapping the script and the rest of the HTML around so you have:
<!-- rest of dynamically loaded HTML -->
<script type="text/javascript">
// Your code here
</script>
This forces the browser to only process your code once it has loaded every other DOM element in the dynamically loaded HTML. Of course this means you'll have to make sure the inserted HTML does not have unintended UI consequences by using CSS/HTML instead of JS. Its an old Javascript trick from years gone by. As a bonus, you don't need jQuery for this anymore.
I should mention that in Chromium v34, putting a second $(document).ready call inside a <script> tag in the dynamically loaded HTML seems to wait for dynamically loaded DOM to load and then runs the function as you described. I'm not sure this behaviour is standard though as it has caused me great grief when trying to automate tests with this kind of code in it.
JQuery AJAX .load() has a built-in feature for handling this.
Instead of simply $('div#content').load('such_a_such.url'); you should include a callback function. JQuery .load() provides room for the following:
$('div#content').load('such_a_such.url',
{ data1: "First Data Parameter",
data2: 2,
data3: "etc" },
function(){ $('#span1').text("This function is the equivalent of");
$('#span2').text("the $(document).ready function.");
}
);
However, you do not need to include the data argument.
$( "#result" ).load( "ajax/test.html", function() {
alert( "Load was performed." );
});
http://api.jquery.com/load/
So i have the same piece of code that runs for both Ready and Click events, but when I try to combine them it doesn't work
$("input[name='reimburse']").on("ready click", function() {
//some code
});
I think it has to do it the Ready function because even this doesn't work
$("input[name='reimburse']").on("ready", function() {
//some code
});
Instead I have to do this for Ready functionality
$("input[name='reimburse']").ready(function() {
//some code
});
Other than creating another JS function and calling that method from 2 different declared events, how can I achieve my initial code? Why doesn't calling on("ready") work?
EDIT:
Its been brought to my attention that ready event is not applicable for individual DOM's and that load should be used instead. I have tried this but still doesn't work. Only the click event works. I have also tried replacing on with bind and same thing happens.
The ready event applies to the document, not to individual DOM elements. So, there is no specific ready event that applies to the "input[name='reimburse']" DOM elements.
If what you're trying to do is to have the same function fire both when the page is first loaded and when a specific click event is fired, then you can put your common event handling code into a named function and then refer to that function from two separate event handlers:
function myHandler(e) {
// code here
}
$(document).ready(myHandler);
$("input[name='reimburse']").on("click", myHandler);
Though, the last line of code above will only work IF those DOM elements are already loaded. As such, you may need to put that line of code inside a .ready() handler (depending upon where the code is being run from).
$(document).ready(function() {
$("input[name='reimburse']").on("click", myHandler);
myHandler();
});
Here's another related answer: jQuery.ready() equivalent event listener on elements?
Why doesn't calling on("ready") work?
Because jQuery decided not to support that structure. jQuery used to support $(document).on( "ready", handler ), but as of jQuery v1.8, that support has been deprecated (e.g. you shouldn't use it because it will be removed). Per the jQuery documentation, these three forms can be used for .ready().
$( document ).ready( handler )
$().ready( handler ) // works, but not recommended
$( handler )
If it is bothering you to have to both specify an event handler and call your function at initiatialization time, then you could create your own plug-in that would do that for you:
$.fn.initOn = function(events, handler) {
this.on(events, handler);
handler();
}
Then, instead of this:
$(document).ready(function() {
$("input[name='reimburse']").on("click", myHandler);
myHandler();
});
You could just do this:
$(document).ready(function() {
$("input[name='reimburse']").initOn("click", myHandler);
});
You can just imitate the click on ready:
jQuery(document).ready(function () {
$("input[name='reimburse']").click(function() {
//some code
});
$("input[name='reimburse']").click();
});
Try using bind()
$("input[name='reimburse']").bind("ready click", function() {
//some code
});
According to the documentation
Multiple event types can be bound at once by including each one
separated by a space
Note, ready is valid for document and shouldn't be used for elements. To get similar functionality, use load
$("input[name='reimburse']").bind("load click", function() {
//some code
});
From the jQuery docs here: https://api.jquery.com/ready/
There is also $(document).on( "ready", handler ), deprecated as of jQuery 1.8. This behaves similarly to the ready method but if the ready event has already fired and you try to .on( "ready" ) the bound handler will not be executed. Ready handlers bound this way are executed after any bound by the other three methods above.
While you shouldn't be using deprecated methods whenever possible, I'm curious, where are you setting your event listeners?
I want to use jQuery ready() function for the document element. Here are my scripts:
1st page:
$(document).ready(function(){
$('form#haberekle').ajaxForm(options);
});
2nd page:
$(document).ready(function() {
var options = {
success:showResponse,
beforeSubmit:showRequest,
resetForm:true
};
$('#haberresmiekleform').ajaxForm(options);
});
These two pages are included in the same main page with <!--#include file=""-->
Can these two functions work properly, or they block each other?
According to my experience they seem work properly.
For example: an onclick function of a button is only one.
You can have as many .ready() calls as you want, jQuery is designed with this in mind and it's absolutely ok.
So yes, it is ok, and you won't have any problems...this happens all the time.
Think of it as an event handler, like .click(), this is exactly how it behaves (well, strictly speaking, not exactly, but for most purposes like this). So you can have as many as you want.
One more note that may be of interest, the handlers you pass into .ready() are pushed via .done() to the readyList, which means they'll execute in the order you called them in the page. The same order behavior is true (though via an array, a different method) in earlier versions of jQuery.
Yes, that is fine. Both will be called when the dom is fully loaded. Note that if you call .ready() after the dom is already loaded, the callback will be executed immediately. See http://api.jquery.com/ready/
Yes, you can.
Take a look here:
http://www.learningjquery.com/2006/09/multiple-document-ready
No problem attaching several handlers for the same event. The documentation for ready says :
There is also
$(document).bind("ready", handler).
This behaves similarly to the ready
method but with one exception: If the
ready event has already fired and you
try to .bind("ready") the bound
handler will not be executed.
And the documentation for bind says:
When an event reaches an element, all
handlers bound to that event type for
the element are fired. If there are
multiple handlers registered, they
will always execute in the order in
which they were bound
I'm still new to jQuery and I'm wondering how come the jQuery functions called inside .ready() work just fine but not outside?
For example, this would work:
$(document).ready(function() {
$('#field1').click(function() {
$('#result').load('/random_post #post');
});
});
But this won't:
$('#field1').click(function() {
$('#result').load('/random_post #post');
});
You cannot access the DOM until the document is fully parsed and the DOM constructed. That includes modifying any elements – such as #field1 and #result.
Since $(document).ready(..) is long and may be hard to remember, you can also use the short form $(onReadyFunction), i.e.
$(function() {
$('#field1').click(function() {
$('#result').load('/random_post #post');
});
});
By the way, jQuery does no magic here: It just registers your function to be called when DOMContentLoaded (or equivalent) event is triggered by the parsing and construction of the DOM tree.
How and if it works will depend on the order of which scripts and elements are laid out in your HTML, and it might also be affected by parameters outside your control (e.g. how the browser is programmed to behave).
I 'd hazard a guess that this script appears in your page before the element with id="field1" that gets a click handler added; this causes the script to run and find no such element in the document tree (yet). The element gets added after the script runs, which is why jQuery finds it just fine after the whole document has loaded.
If you move this script at the very end of your page it should work (although of course the correct solution is to use the document ready event, as in your first snippet).
The ready function is executed when the dom tree has been created. You get an error in your second piece of code because the dom tree element with id filed1 has not been created yet, i.e. the page hasn't loaded yet.