check if an element does not contain a class in JavaScript [duplicate]

Question

Hello friends I have this code that works well for me to check if my element contains a certain class, but I want to achieve the opposite, that it checks me when this class does not contain the element.

if (document.querySelector(".header").classList.contains("no-sticky")) {
      alert();
    }

Answer 1

Just put exclamation mark in front of the condition.

if (!document.querySelector(".header").classList.contains("no-sticky")) {
      alert();
    }```