add class from jquery code example

Example 1: add class jquery

$("#my_id").attr("class", "my_new_class_name");

Example 2: jquery addclass

$( "p" ).removeClass( "myClass noClass" ).addClass( "yourClass" );

Example 3: javascript add class to element

var someElement= document.getElementById("myElement");
    someElement.className += " newclass";//add "newclass" to element (space in front is important)