Make HTML Checkboxes behave like Radio Inputs in that only one can be selected at a time.

checkboxradio.js

(function(w) {
  
  function checkboxAsRadio(selector) {
    return function (event) {
      var el = event.target;
      
      // only proceed if we have a matching checkbox
      if (!(el instanceof HTMLInputElement && el.matches(selector))) {
        return;
      }
      
      // close all open checkboxes with the same name attribute
      if (el.checked) {
        Array
          .from(document.querySelectorAll('input[name=' + el.name + ']'))
          .filter(function (checkbox) {
            return checkbox.checked && checkbox !== el;
          })
          .map(function (checkbox) {
            checkbox.checked = false;
          });
      }
    };
  }
  
  document.addEventListener('change', checkboxAsRadio('.checkbox-as-radio'));
  
}(this));

package.json

{
  "name": "checkboxradio",
  "version": "0.1.1"
}