naive query string parser

parseQueryString.js

function parseQueryString(qs) {
  return (
    qs.slice(1).split('&')
      .map((pair) => {
        const [key, value] = pair.split('=');
        let transformedValue = decodeURIComponent(value);
        if (/^[{|\]]/.test(transformedValue)) {
          transformedValue = JSON.parse(transformedValue);
        }
        return { key: key, value: transformedValue };
      })
      .reduce((prev, curr) => {
        const { key, value } = curr;
        const next = {};
        next[key] = value;
        return Object.assign({}, prev, next);
      }, {})
  );
}