jQuery Hello World

JQuery is the most popular Javascript Library . It is a powerful JavaScript API which makes it a lot easier to perform various standard JavaScript actions in your HTML page. All the power of jQuery is accessed via JavaScript, so having a strong grasp of JavaScript is essential for understanding, structuring, and debugging your code. A "HELLO WORLD!!" is a simple program that outputs "HELLO WORLD!!" on the screen. Since it's a very simple program, it's often used to introduce a new programming to a newbie. Let's go over the "HELLO WORLD!!" program, which simply prints "HELLO WORLD!!" in a messeagebox.
$(document).ready(function(){ $("#myButton").click(function(){ alert("HELLO WORLD!!"); }); });
<button id="myButton">Click Here</button>
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<html> <head> <title>Hello World</title> <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <script type="text/javascript"> $(document).ready(function(){ $("#myButton").click(function(){ alert("HELLO WORLD!!"); }); }); </script> </head> <body> <button id="myButton">Click Here</button> </body> </html>

Adding jQuery to Your Web Page

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

The above line shows how to include jQuery from a CDN, like Google.

Document Ready Event

$(document).ready(function(){ });
Here $() indicates jQuery syntax and is used to define jQuery part. $(document).ready() method get called when document is loaded.
$("#myButton").click(function(){ alert("HELLO WORLD!!"); });
We have used jQuery selector here. $(#myButton) actually selects DOM element with that id, so $(#myButton) selects button and when we click on that button,click function will get called, then we called the alert function with message "HELLO WORLD!!" .