@gitlab/ui/dist/directives/resize_observer/resize_observer.js

GitLab UI Components

import ResizeObserver from 'resize-observer-polyfill';
import isFunction from 'lodash/isFunction';

// more information: https://github.com/WICG/ResizeObserver/issues/59

var observer = new ResizeObserver(function (entries) {
  entries.forEach(function (event) {
    event.target.glResizeHandler(event);
  });
});
var ResizeObserverDirective = {
  bind: function bind(el, _ref) {
    var resizeHandler = _ref.value;

    if (!isFunction(resizeHandler)) {
      throw TypeError('directive value must be a function');
    }

    el.glResizeHandler = resizeHandler;
    observer.observe(el);
  },
  unbind: function unbind(el) {
    if (el.glResizeHandler) {
      delete el.glResizeHandler;
      observer.unobserve(el);
    }
  }
};

export default ResizeObserverDirective;