how to always check if the class exists in jquery 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: if a class exists jquery

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