Basics. Source: http://www.catswhocode.com/blog/manipulating-the-dom-with-jquery-10-useful-code-snippets

basics.js

//Add a CSS class to a specific element
$('#myelement').addClass('myclass');

//Removing a CSS class from a specific element
$('#myelement').removeClass('myclass');

//Check if a specific element has a CSS class
$(id).hasClass(class)

//Switch CSS using jQuery
$('link[media='screen']').attr('href', 'Alternative.css');

//Append HTML to an element
$('#lal').append('sometext');

//$('#lal').append('sometext');
if ($('img').length) {
    log('We found img elements on the page using "img"');
} else {
    log('No img elements found');
}


//Get the parent element of an element
var id = $("button").closest("div").attr("id");

//Get element siblings
$("div").siblings()

//Remove an option from a select list
$("#selectList option[value='2']").remove();


//Get the selected option as text
$('#selectList :selected').text();


//Apply a “zebra” effect on tables
$("tr:odd").addClass("odd");

//Count children of an element
$("#foo > div").length