Make multiselect fields the full height of number of items with Vanilla JS

fullHeightMultiselectFields.js

// Select the multiselect fields
var mulitSelectFields = document.querySelectorAll('select[multiple]');
// For each field found...
Array.prototype.forEach.call(mulitSelectFields, function(el, i) {
  // count how many selection options are present
  var itemsInSelect = el.length;
  // then set the height with the size attribute to match
  el.setAttribute('size', itemsInSelect);
  // finally remove the scroll indicator for that field
  el.style.overflowY = 'auto';
});