Answer 1

Set data attribute for each list items, use JavaScript dataset to identify clicked list item.
function whit() {
var liItems = document.querySelectorAll("#tabs li");
liItems.forEach( function(e) {
e.addEventListener("click",changeActive.bind(e));
}); // if not support ES6, please use iterator
}
function changeActive() {
alert(this.dataset.page); //access data-page attribute of clicked item
}
https://code.sololearn.com/W6G5zGe2emZk/?ref=app