.js

exports.handler = (event, context, cb) => {
  const projects = new Projects(event);

  switch (event.method) {
    case 'POST':
      Promise.resolve()
      .then(() => projects.postCheckInput())
      .then(() => projects.checkMaxUse())
      .then(() => projects.post())
      .then((data) => cb(null, data))
      .catch((error) => errorHandle(error, cb));
      break;
    case 'GET':
      Promise.resolve()
      .then(() => projects.get())
      .then((data) => cb(null, data))
      .catch((error) => errorHandle(error, cb));     
      break;
    case 'DELETE':
      Promise.resolve()
      .then(() => projects.checkOwnSite())
      .then(() => projects.delete())
      .then((data) => cb(null, data))
      .catch((error) => errorHandle(error, cb));
      break;
    case 'PUT':
      Promise.resolve()
      .then(() => projects.checkOwnSite())
      .then(() => projects.updateProjectName())
      .then((data) => cb(null, data))
      .catch((error) => errorHandle(error, cb));
      break;
  }
};