collect dataset attributes from a dom element

getDataset.js

const getDataset = (elem) => {
  /* ie <= 10 does not support elem.dataset
   * ie <= 10 also doesn't support Array.from
   * collect an elements data properties and return them in a similar format
   * to the elem.dataset method
   */

  let attrs = Array.prototype.slice.call(elem.attributes).filter(attr => !!~attr.nodeName.indexOf('data-'));

   return attrs.reduce((a, attr) => {
    let props = {};
    props[attr.nodeName.substring(5)] = attr.value;
    return {
      ...a,
      ...props,
    }
  }, {});
}