Selectors

Basic Selectors

$("p") // all

elements $(".btn") // class selector $("#main") // ID selector $("ul > li") // direct children $("input[type='text']") // attribute selector

Common Selectors

$('*')	All elements
$('a, span')	Multiple selectors
$(':first')	First matched element
$(':last')	Last matched element
$(':even') / $(':odd')	Even/odd indexed elements
$(':visible') / $(':hidden')	Visibility filters
$(':contains(text)')	Elements containing text
$(':has(selector)')	Elements containing selector match

DOM Manipulation

Content & Structure

$("#el").html("Bold");   // set inner HTML
$("#el").text("Plain text");     // set text content
$("ul").append("New
");  // add at end
$("ul").prepend("First
"); // add at start

Insert & Remove

$("

Hello

").insertAfter("#el"); // insert after $("

").insertBefore("#el"); // insert before $("#el").remove(); // remove element from DOM $("#el").empty(); // remove all children

Methods

.html()	Get/set inner HTML
.text()	Get/set text content
.append() / .prepend()	Add child at end/start
.after() / .before()	Insert sibling after/before
.wrap()	Wrap element with new parent
.clone()	Deep copy element
.replaceWith()	Replace element

Events

Binding Events

$(".btn").on("click", function () {
  $(this).toggleClass("active");
});
$(document).on("click", ".dynamic", handler); // delegation
$(".btn").off("click"); // remove handler

Shorthand Methods

.click(fn)	Click handler
.hover(fnIn, fnOut)	Mouse enter/leave
.focus() / .blur()	Focus gained/lost
.change(fn)	Value changed (input/select)
.submit(fn)	Form submission
.keydown() / .keyup()	Keyboard events

Document Ready

$(document).ready(function () { /* DOM loaded */ });
$(function () { /* shorthand */ });

Effects & Animation

Show / Hide / Toggle

$("#el").hide(400);          // hide with animation
$("#el").show(400);          // show with animation
$("#el").toggle();           // toggle visibility
$("#el").fadeIn(600);        // fade in
$("#el").slideDown(400);     // slide down

Custom Animation

$("#el").animate({
  opacity: 0.5,
  left: "+=50px",
  height: "toggle"
}, 1000, function () { /* complete */ });

Effect Methods

.fadeIn() / .fadeOut()	Animate opacity
.fadeToggle()	Toggle with fade
.slideDown() / .slideUp()	Animate height
.animate(props, ms)	Custom CSS animation
.stop()	Stop current animation
.delay(ms)	Delay next queued effect

AJAX

Shorthand Methods

$.get("/api/data", function (data) { console.log(data); });
$.post("/api/data", { name: "Alice" }, function (res) {});
$.getJSON("/api/items", function (json) {});
$("#el").load("/fragment.html"); // load HTML into element

Full $.ajax

$.ajax({
  url: "/api/data",
  method: "POST",
  data: JSON.stringify({ key: "val" }),
  contentType: "application/json",
  success: (res) => console.log(res),
  error: (xhr) => console.error(xhr.status)
});

AJAX Options

url	Request URL
method	HTTP method (GET, POST, ...)
data	Data to send
dataType	Expected response type
contentType	Request content type
success / error	Callback functions
headers	Custom request headers

Traversal

Tree Navigation

$("li").parent();           // direct parent
$("li").parents("ul");      // all matching ancestors
$("ul").children("li");     // direct children
$("ul").find(".active");    // all matching descendants
$("li").siblings();         // sibling elements

Traversal Methods

.parent() / .parents()	Direct parent / all ancestors
.children() / .find()	Direct children / all descendants
.siblings()	All sibling elements
.next() / .prev()	Next/previous sibling
.closest(sel)	Nearest ancestor matching selector
.first() / .last()	First/last in matched set
.eq(index)	Element at index
.filter(sel)	Reduce to matching elements

Attributes & CSS

Attributes

$("img").attr("src");              // get attribute
$("img").attr("src", "new.jpg");   // set attribute
$("img").removeAttr("title");      // remove attribute
$("input").prop("checked", true);  // set property

CSS & Classes

$(".box").css("color", "red");     // set single style
$(".box").css({ color: "red", fontSize: "14px" }); // multi
$("p").addClass("highlight");
$("p").removeClass("highlight");
$("p").toggleClass("active");
$("p").hasClass("active");         // returns boolean

Forms

Values & Serialization

$("input").val();              // get value
$("input").val("new value");   // set value
$("form").serialize();         // "name=Alice&age=30"
$("form").serializeArray();    // [{name, value}, ...]

Form Selectors

$(":input")	All form elements
$(":checked")	Checked checkboxes/radios
$(":selected")	Selected option elements
$(":disabled")	Disabled elements
$(":text")	Text inputs

Utilities

Array & Object Helpers

$.each([1, 2, 3], function (i, val) { /* iterate */ });
$.each(obj, function (key, val) { /* iterate object */ });
$.extend({}, defaults, options); // merge objects
$.inArray("b", ["a", "b", "c"]); // returns 1 (index)

Utility Methods

$.each(arr, fn)	Iterate array or object
$.extend(target, ...)	Merge objects (shallow)
$.inArray(val, arr)	Index of value (-1 if missing)
$.isArray(obj)	Check if array
$.trim(str)	Remove leading/trailing whitespace
$.parseJSON(str)	Parse JSON string
$.map(arr, fn)	Transform array elements

Common Patterns

Chaining

$("ul")
  .find("li")
  .addClass("item")
  .first()
  .css("font-weight", "bold");

Plugin Pattern

$.fn.highlight = function (color) {
  return this.each(function () {
    $(this).css("background", color || "yellow");
  });
};
$("p").highlight("pink");

Conflict Resolution

// Avoid $ conflicts with other libraries
jQuery.noConflict();
jQuery(document).ready(function ($) {
  $(".btn").click(handler); // $ safe inside
});

JQUERY QUICK REFERENCE