index.js

router.put("/v1/users/:id", async (context) => {
  if (!context.params || !context.params.id ||
    isNaN(parseInt(context.params.id) || !context.request.hasBody)) {
    context.response.status = 400;
    context.response.body = { error: "Invalid request" };
  } else {
    const result = getById(context.params.id);
    if (result.length < 1) {
      context.response.status = 404;
      context.response.body = { error: `User ${context.params.id} not found` };
    } else {
      const id = context.params.id;
      const { firstName, lastName, age } = (await context.request.body()).value
      const ageInt = parseInt(age);
      if (firstName && lastName && ageInt) {
        dummyUsers.splice(id - 1, 1, { id: id, firstName: firstName, lastName: lastName, age: ageInt });
        context.response.status = 200;
        context.response.body = dummyUsers[id-1];
      } else {
        context.response.status = 400;
        context.response.body = { error: "Invalid payload's provided" };
      }
    }
  }
})