tabs.js

document.addEventListener('DOMContentLoaded', function(){

var tabs = {
  tab1: document.getElementById('tab-link-1'),
  tab2: document.getElementById('tab-link-2'), 
  tab3: document.getElementById('tab-link-3'),
  tab4: document.getElementById('tab-link-4')
}

var content = {
  one: document.getElementById("tab-content-1"),
  two: document.getElementById("tab-content-2"),
  three: document.getElementById("tab-content-3"),
  four: document.getElementById("tab-content-4")
}

for (tab in tabs) {
  if(tabs[tab]) {
    tabs[tab].addEventListener('click', function(event) {
      event.preventDefault();
      var $this = this;
      clearSelected();
      $this.classList.add("selected");

      clearActive();

      if ($this.id === "tab-link-1") {
        content.one.classList.add("active");
      } else if ($this.id === "tab-link-2") {
        content.two.classList.add("active");
      } else if ($this.id === "tab-link-3") {
        content.three.classList.add("active");
      } else {
        content.four.classList.add("active");
      }
    });
  }
}
var has_edd_error = document.getElementsByClassName('edd-alert');
if (has_edd_error.length > 0) {
  clearSelected();
  tabs.tab4.classList.add("selected");
  clearActive();
  content.four.classList.add("active");
}

function clearSelected() {
  for (tab in tabs) {
    tabs[tab].classList.remove("selected");
  }
}
function clearActive() {
  for (element in content) {
    content[element].classList.remove("active");
  }
}
});