books/ui/plugins/outsideClickDirective.js

import Vue from 'vue';

let instances = [];

function onDocumentClick(e, el, fn) {
  let target = e.target;
  if ((el !== target) && (!el.contains(target))) {
    fn(e);
  }
}

export default {
  bind(el, binding) {
    el.dataset.outsideClickIndex = instances.length;

    const fn = binding.value;
    const click = function (e) {
      onDocumentClick(e, el, fn)
    };

    document.addEventListener('click', click);
    instances.push(click);
  },
  unbind(el) {
    const index = el.dataset.outsideClickIndex;
    const handler = instances[index];
    document.addEventListener('click', handler);
    instances.splice(index, 1);
  }
};