Why Use is JavaScript Library and Frameworks
In essence, libraries and frameworks are sets of pre written JavaScript code that programmers can utilize for their applications. They are primarily used to expedite the development process, streamline routine tasks, and offer a strong framework or foundation for creating applications.
Differences Between Libraries and Frameworks
Despite being pre-programmed code, their approaches and scopes are different.
Libraries: Usually, libraries are made to provide functionality for a certain job or to address a single issue. When necessary, you can utilize the capabilities they provide in your code. The entire application flow is under your control as the developer, and you choose when and when to invoke the library’s functions. Consider a library as offering specialized.
Frameworks: Although they are also pre-programmed, frameworks often organize a long list of items. They offer a conventional solution that frequently has some restrictions and typically governs how you organize your application. A framework offers a good starting point and typically requires a specific file layout. Frameworks are frequently collections of libraries that offer a single or multiple-use solution. There are a lot of things you can do with your web apps that frameworks can help you with.
In theory, if you ignore time, you can’t accomplish anything more with frameworks and libraries than you could without them. Their appeal can be explained by the fact that they enable developers to produce higher-quality work much more quickly.
Examples of Popular Libraries/Frameworks
Several well-known JavaScript libraries and frameworks:
- Libraries: jQuery, D3, Underscore, React, QUnit.
- Frameworks: Angular, Backbone, Ember, Famo.us, Knockout, Svelte.
- Runtime Environments / Backend: Node.js, a runtime environment that allows JavaScript to execute outside the browser, is commonly discussed alongside frameworks and tools for backend development. Express is considered as the most widely used Node.js framework.
jQuery Basics
Perhaps the most well-known JavaScript library is jQuery. According to some reports, it was the most popular JavaScript framework (actually a library). Many JavaScript coders use jQuery, which is used by many famous websites. To simplify DOM interaction, event management, and AJAX queries. It streamlines JavaScript concerns like browser compatibility, especially with older browsers. Despite current JavaScript (“vanilla JavaScript”) being able to accomplish many of jQuery’s tasks, it’s still widely utilized in older codebases, making it vital to know.
Once you understand JavaScript, learning the fundamentals of jQuery is said to be simple.
Including jQuery
You must include the jQuery library in your web pages before you can begin using jQuery. Using a version hosted on a content delivery network (CDN) is the simplest method. Downloading the library and hosting it yourself is the alternative.
Using a <script> element, usually in the <head> or at the end of the <body>, you include the library in your HTML file. It frequently comes via a publicly accessible CDN URL.
Example of including jQuery from a CDN (version numbers may vary):
<script src=”https://code.jquery.com/jquery-3.6.0.min.js”></script>
You must include jQuery before any of your own JavaScript code that uses it.
The jQuery Function and Object ($())
The single global function jQuery(), which has the shorter alias $(), provides access to all of jQuery’s features. The same function is denoted by these two names. The shortness of $ makes it the favored method. Additionally, this function acts as the namespace for utility functions in jQuery.
The $(…) function usually returns a jQuery object when called. A group of zero or more DOM elements is represented by a jQuery object.
There are other ways to call the $(…) function:
- With a CSS selector string: The most popular method is this one. It produces a jQuery object with the elements it has selected from the document that match the selector.
- Any other CSS selector, even more intricate chained ones, can be used. Context can be provided via an optional second argument, which restricts the search to descendants of designated elements.
- With HTML: Based on the supplied HTML text, this generates new DOM elements with HTML and returns a jQuery object with these new elements.
- With a function: When the document has finished loading and is prepared for manipulation, this registers the function to be run.
- Sometimes, the shortcut $(function() {… }); will be used to write this.
- With existing DOM elements or a jQuery object: This creates a new jQuery object that encapsulates existing DOM elements or another jQuery object.
Prefixing variables containing jQuery objects with a dollar sign ($) is standard practice.
Manipulating Elements
You can use jQuery methods to take actions on a jQuery object, which is a chosen collection of items. All of the elements in the chosen set are implicitly affected by jQuery methods. This is a crucial feature: jQuery manages the iteration for you, whereas the normal DOM API frequently requires you to loop through a group of components manually.
Changing styles, characteristics, and content are examples of common manipulation chores.
Changing Content: The text or HTML content of the chosen components can be changed using methods like text() and html(). HTML() is comparable to innerHTML, and text() is comparable to textContent.
Changing Attributes: HTML attributes can be set or retrieved using the attr() method.
Changing CSS Styles/Classes: CSS classes are managed via addClass(), removeClass(), and toggleClass(), whereas inline styles are changed by methods like css().
Adding/Removing Elements: The document structure can be changed using methods like append(), prepend(), before(), after(), and remove().
Method Chaining
The jQuery object that was called upon is returned by many jQuery functions. This enables you to use a popular and effective jQuery programming idiom: chaining several method calls together in a single sentence.
Example of chaining:
$(“#pageHeader”).text(“Hello, world!”).css(“color”, “red”).css(“font‐size”, “60px”);
This selects the element, sets its text, then sets its color, and finally sets its font size.
Events
An easier and cross-browser compatible method of handling events is offered by jQuery. The main technique for attaching event handlers is the on() method. Additionally, there are other shorthand methods for common events, such as keydown(), mouseover(), and click().
Example using a shorthand event method:
$(“#hidebutton”).click(function () { // Attaches a click handler to the element with ID “hidebutton”
$(“p”).hide(); // Hides all paragraphs when the button is clicked
});
Example using on():
$(‘a’).on(‘click’, function() { /* … handler code … */ });
Effects
Adding animations and visual effects is simple with jQuery. There are basic effects like fading, hiding, and revealing elements.
More intricate custom animations can be created using the animate() method.
Example using simple effects:
$(“.easy”).show(); // Shows elements with class “easy”
$(“p”).hide(); // Hides all paragraphs
$(“p.details”).show(“fast”); // Shows elements with class “details” quickly (“fast” is a duration keyword)
Example using fading effects:
$(‘.target’).fadeIn(); // Fades in the selected element
Example using sliding effects:
$(‘#helloDiv’).slideDown(‘slow’); // Slides down the element with ID “helloDiv” slowly
AJAX
Asynchronous JavaScript and XML (AJAX) queries, which are used to load data from a server without completely refreshing the page, are made easier with jQuery. Even though the initial acronym for AJAX was “Asynchronous JavaScript and XML,” JSON is now more frequently utilized than XML.
Utility functions for AJAX, including $.ajax() (the most complex and general), $.get(), $.post(), $.getJSON(), and $.getScript(), are provided by jQuery. These asynchronous operations usually handle the server’s response using Promises or callback methods.
Example using $.get() with a callback function:
$.get( “getdata.html”, function( data ) {
$( “.result” ).html( data );
});
Example using $.get() with Promises (recommended way to handle server response):
$.get(‘http://localhost:7070’).then(
// successful return
function(data) { /* … process data … */ },
// error handler
function(jqXHR, textStatus, err) { console.error(err); }
);
The $.ajax() function allows detailed configuration of the AJAX request via an options object.
In conclusion, even though its function has evolved with the development of contemporary JavaScript and browser capabilities, jQuery offers a full suite of tools and a more efficient syntax for common web development tasks, making interactions with the browser’s DOM, events, and AJAX simpler and managing browser inconsistencies.