index.js

function getPullRequestBranch(payload) {
  return pullRequestBranch = delve(payload, 'pull_request.head.ref');
}

function getBaseBranch(payload) {
  return baseBranch = delve(payload, 'pull_request.base.ref');
}

function getCommitURL(payload) {
  return commitURL = delve(payload, 'pull_request.statuses_url');
}

function getAction(payload) {
  return commitURL = delve(payload, 'action');
}