Preview:
var getLi = document.querySelectorAll('.custom-menu-primary .hs-menu-wrapper > ul > li a');
  for (var i = 0; i < getLi.length; i++) {
    var className = getLi[i].innerText;
    var addClassName = className.replace(/\s+/g, "_");
    if (addClassName.length != 0) {
      getLi[i].parentNode.classList.add(addClassName.toLowerCase());
    }
  }
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