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There is no difference in functionality between your examples - they both bind to DOM ready. For reference, there are two points at which you can bind your jQuery code. The first will execute when the DOM is ready (both are equivalent): // full example $(document).
jQuery document ready is used to initialize jQuery/JavaScript code after the DOM is ready, and is used most times when working with jQuery. The Javascript/jQuery code inside the $(document). ready() function will load after the DOM is loaded, yet before the page contents load.
The key difference between $(document). ready() and $(window). load() event is that the code included inside onload function will run once the entire page(images, iframes, stylesheets,etc) are loaded whereas the $(document). ready() event fires before all images,iframes etc.
There is also $(document). on( "ready", handler ) , deprecated as of jQuery 1.8 and removed in jQuery 3.0. Note that if the DOM becomes ready before this event is attached, the handler will not be executed.
$(document).ready(function(){ ... }); or short $(function(){...});
This Function is called when the DOM is ready which means, you can start to query elements for instance. .ready() will use different ways on different browsers to make sure that the DOM really IS ready.
(function(){ ... })();
That is nothing else than a function that invokes itself as soon as possible when the browser is interpreting your ecma-/javascript. Therefor, its very unlikely that you can successfully act on DOM elements here.
(function(){...})(); will be executed as soon as it is encountered in the Javascript.
$(document).ready() will be executed once the document is loaded. $(function(){...}); is a shortcut for $(document).ready() and does the exact same thing.
The following code will be executed when the DOM (Document object model) is ready for JavaScript code to execute.
$(document).ready(function(){
// Write code here
});
The short hand for the above code is:
$(function(){
// write code here
});
The code shown below is a self-invoking anonymous JavaScript function, and will be executed as soon as browser interprets it:
(function(){
//write code here
})(); // It is the parenthesis here that call the function.
The jQuery self-invoking function shown below, passes the global jQuery object as an argument
to function($). This enables $ to be used locally within the self-invoking function without needing
to traverse the global scope for a definition. jQuery is not the only library that makes use of $, so this
reduces potential naming conflicts.
(function($){
//some code
})(jQuery);
$(document).ready(function() { ... }); simply binds that function to the ready event of the document, so, as you said, when the document loads, the event triggers.
(function($) { ... })(jQuery); is actually a construct of Javascript, and all that piece of code does is pass the jQuery object into function($) as a parameter and runs the function, so inside that function, $ always refers to the jQuery object. This can help resolve namespacing conflicts, etc.
So #1 is executed when the document is loaded, while #2 is run immediately, with the jQuery object named $ as shorthand.
document.ready run after DOM is "constructed". Self-invoking functions runs instantly - if inserted into <head>, before DOM is constructed.
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