Listen for CSS class change in pure JS - Mutation Observer

Listen for CSS class change in pure JS - Mutation Observer.md

https://blog.sessionstack.com/how-javascript-works-tracking-changes-in-the-dom-using-mutationobserver-86adc7446401

https://developer.mozilla.org/en-US/docs/Web/API/MutationRecord

// ========================================== get rid of body scroll:
var mutationObserver = new MutationObserver(function(mutations) {
  mutations.forEach(function(mutation) {
    console.log(mutation);
    console.log(mutation.oldValue);
    if (mutation.oldValue === 'search-trigger') {
      document.getElementsByTagName('body')[0].classList.add('noscroll');
    } else {
      document.getElementsByTagName('body')[0].classList.remove('noscroll');
    }
  });
});

// Starts listening for changes in the '.search-trigger' HTML element
mutationObserver.observe(document.querySelector('.search-trigger'), {
  attributes: true,
  characterData: true,
  childList: true,
  subtree: true,
  attributeOldValue: true,
  characterDataOldValue: true
});
// ========================================== get rid of body scroll ENDS