jquery how to check if it contains the class code example

Example 1: jquery check if a class exists

if ($(".mydivclass")[0]){
    // Do something if class exists
} else {
    // Do something if class does not exist
}

Example 2: jquery check if element has class starting with

/* Answer to: "jquery check if element has class starting with" */

if(!$(this).is('[class*="answerbox"]')) {
    //Finds element with no answerbox class
} else {
    //The element has already an answerbox class
}