jQuery is a fast, small, and feature-rich JavaScript library. It simplifies things like HTML document traversal and manipulation, event handling, and animation.

jQuery can be included in a project by adding a <script> tag in the HTML file, either via a CDN link or by downloading and linking a local copy.

$(document).ready() is a jQuery event that runs a function when the DOM is fully loaded, ensuring that the code inside is executed only after the HTML document is ready.

$(document).ready() fires when the DOM is loaded, whereas $(window).load() fires after all content, including images and iframes, is fully loaded.

Use the $ function with a CSS selector as an argument, e.g., $('div') selects all <div> elements.

Use the .hide() method, e.g., $('#element').hide()

Use the .show() method, e.g., $('#element').show()

Use the .toggle() method, e.g., $('#element').toggle().

The .css() method is used to get or set CSS properties of elements. For example, $('#element').css('color', 'red') sets the color of the selected element to red.

Use the .addClass() method, e.g., $('#element').addClass('newClass').

Use the .removeClass() method, e.g., $('#element').removeClass('oldClass').

The .on() method is used to attach event handlers to elements. For example, $('#element').on('click', function(){}) attaches a click event handler to the selected element.

Use the .on() method with an object of event types and handlers, e.g., $('#element').on({click: function(){}, mouseenter: function(){}}).

Event delegation is a technique where you attach a single event listener to a parent element instead of each child element. This is efficient for dynamically added elements.

Use the $.ajax() method, e.g., $.ajax({url: 'file.php', type: 'GET', success: function(data){}}).

Use $.get() for GET requests and $.post() for POST requests.

Use the $.each() method, e.g., $.each(array, function(index, value){}).

Use the .val() method, e.g., $('#inputField').val().

Use the .val() method with an argument, e.g., $('#inputField').val('newValue').

The .html() method gets or sets the HTML content of an element. For example, $('#element').html() returns the HTML content, while $('#element').html('<p>New Content</p>') sets new HTML content.

Use the .remove() method, e.g., $('#element').remove().

.remove() removes the element and its data, while .detach() removes the element but keeps its data and events in memory, allowing for reattachment.

Use the .append() method, e.g., $('#element').append('<p>New Content</p>').

Use the .prepend() method, e.g., $('#element').prepend('<p>New Content</p>').

Use the .animate() method, e.g., $('#element').animate({left: '100px'}, 500).

The .fadeIn() method gradually changes the opacity of an element from hidden to visible.

The .fadeOut() method gradually changes the opacity of an element from visible to hidden.

The .queue() method is used to manage a queue of functions to be executed on a selected element.

Use the .stop() method, e.g., $('#element').stop().

You can check if an element exists by using a selector and checking the .length property, e.g., if ($('#element').length) { // Element exists }.