add class via jquery but only when not exists

I would like to add a class (class="bbox") to a ul-list but only if no class exists. This is what i have so far. How do I check with jquery if a class exists in the ul-tag?

$("ul").addClass("bbox");

Just use $('.selector').addClass("myClass");.

The jQuery add/remove class functions both check for duplicates internally, meaning that calling addClass twice only will add the class once.

If you want to check if a specific class exists then:

 if(!$("ul").hasClass("class-name")){
    $("ul").addClass("bbox");
 }

If you want to check if any class exists:

if ($('ul').attr('class') == '') {
    $("ul").addClass("bbox");
}

karim79 you almost got it !

let me correct you

$("ul:not([class*='bbox'])").addClass("bbox");

You match the tag with absolute no classes, and if ul had other classes the matching wouldn't be made. You got to search for the exactly class you wish to add. Like .hasClass aproach.

hope it helps