$.ajax(<url>,<settings>) Perform an asynchronous HTTP (Ajax) request to <url>.

$._data(<element>,"events") Return the object of events that are attached to a particular element.

$(<function>) Binds a function to be executed when the DOM has finished loading.

$(<html>) Creates DOM elements on the fly from the provided string of raw HTML.

$.parseJSON(<string>) Convert a JSON string into a JavaScript variable.

$.post(<url>,<data>,<callback>,<dataType>) Load data from the server using a HTTP POST request.

<elementName>.<className> Select an <elementName> element with class <className>.

<elementName>#<id> Select the <elementName> element with ID <id>.

<elementSelector> A function call of the form $(<string>), or the value returned by such a call.

<elementSelector>.attr("disabled", true) Disable one or more elements.

<elementSelector>.data() Return all of the data values ("data-<key>" attributes) for the selected element(s).

<elementSelector>.data(<key>) Retrieve the value of the "data-<key>" attribute for the selected element(s).

<elementSelector>.data(<key>,<value>) Store <value> in the element's "data-<key>" attribute.

<elementSelector>.load(<url>,<data>,<callback>) Load data from the location specified by <url>, passing optional <data> as parameters, and place the returned HTML into the matched element(s). Once done, execute optional <callback>.

<elementSelector>.off() Remove all event handlers that were added to the selected elements.

<elementSelector>.on("click", function (e) { <statements> }) Create a click event for one or more elements.

<elementSelector>.one(<events>,<selector>,<data>,<callbackFunction>) Attach a handler to one or more events for the selected elements. The handler is executed at most once per element per event type.

<elementSelector>.submit(<handler>) Bind an event handler to the "submit" JavaScript event.

Facts, Thoughts and Opinions

A Generic Check-All Function with jQuery

function checkAll() { $(":checkbox").each(function () { $(this).attr('checked', true); }); }
function unCheckAll() { $(":checkbox").each(function () { $(this).attr('checked', false); }); }

Count total items in a DropDownList using jQuery

var count = $("#DropDownList1 option").length;

DropDownList selecteditem text using jQuery

$("#ddl option:selected").text()

Using $.extend() to "clone" a non-DOM object

// Define a first object and then use $.extend to create a merged object with a, b, and c
var ob1 = {a: 'hi', b: 'there'}
var ob2 = $.extend(ob1, {c: '!'});

// Modify ob2, but since the property doesn't exist except for ob1's prototype, it directly modifies ob1
ob2.a = 'There';

// In order to "really" clone the non-DOM object, we need to do this
// Note the extra $.extend({}, ob1) that uses a blank object literal as the basis for the object
var ob1 = {a: 'hi', b: 'there'}
var ob2 = $.extend($.extend({}, ob1), {c: '!'});

ob2.a = 'There';