How can I get separation by QueryString?

[JUDONGHYEOK]

Our API Url is GET members/signup/exists?nickname={}(for nickname check) and GET members/signup/exists?username={}(for username check)

I can use req.url.searchParams.get() to get nickname or username

But I don't know how to separate url by QueryString

Please tell how I separate url by QueryString

rest.get(/^http:\/\/localhost:(3000|6006)\/members\/signup\/exists/, (req, res, ctx) => {
    console.log(req.url);
    if (!req.url.searchParams.get('username')) {
      return ctx.fetch(req);
    }
    console.log('usernameRequest');
    const id = req.url.searchParams.get('username');

    const existedID = validMemberEmail.find(member => member.ID === id);

    if (existedID) {
      return res(ctx.status(200), ctx.json({ unique: false }));
    }
    return res(ctx.status(200), ctx.json({ unique: true }));
  }),

  rest.get(/^http:\/\/localhost:(3000|6006)\/members\/signup\/exists/, (req, res, ctx) => {
    console.log('first');
    if (!req.url.searchParams.get('nickname')) {
      const nicknameResponse = ctx.fetch(req);
      console.log(nicknameResponse);
    }
    const id = req.url.searchParams.get('nickname');

    return res(ctx.status(200), ctx.json({ nickname: false }));
  }),