How to remove/hide select options from select-list

Answer 1

You can "hide" the option by moving it to a hidden select element or cached document fragment, then move it back when you want to show it:

var selectTool = (function() {
  var frag = document.createDocumentFragment();
  return {
    hideOpt: function (selectId, optIndex) {
      var sel = document.getElementById(selectId);
      var opt = sel && sel[optIndex];
      console.log(opt);

      if (opt) {
        frag.appendChild(opt);
      }
    },

    showOpt: function (selectId) {
      var sel = document.getElementById(selectId);
      var opt = frag.firstChild;
      if (sel && opt) {
        sel.appendChild(opt);
      }
    }
  }
}());

Then you can hide the 4th option like: