JavaScript

convert.js

function convertQueryToMap(query) {
  const result = {};
  if (!query) return result;
  query.split('&').forEach((pair) => {
    const [pathway, value] = pair.split('=');
    const pathwaySplit = pathway.split('.');
    let obj = result;
    pathwaySplit.forEach((prop, index) => {
      if (index === pathwaySplit.length - 1) {
        obj[prop] = decodeURIComponent(value);
      } else {
        if (!obj[prop]) obj[prop] = {};
        obj = obj[prop];
      }
    });
  });

  return result;
}