Get all the a elements within li elements in the header menu
var aElements = document.querySelectorAll('.allMenu.Left li a');
// Loop through each a element and check if its id matches navclassid
for (var i = 0; i < aElements.length; i++) {
var aElement = aElements[i];
if (aElement.id == navclassid) {
aElement.classList.add('on');
break; // Exit the loop once a match is found
}
}