index.js

const core = require('@actions/core');
const github = require('@actions/github');

try {
  // skip if not PR
  if (github.context.eventName !== "pull_request") {
    console.log("not a PR")
    return
  }

  // skip if PR is not freshly opened
  if (github.context.payload.action !== "opened") {
    console.log("PR is not new")
    return
  }

  const pr_payload = github.context.payload.pull_request;
  const token = core.getInput('github-token');
  let added = parseInt(pr_payload.additions);
  let deleted = parseInt(pr_payload.deletions);

  if (token == "") {
    throw new Error("no gh token");
  }

  const octokit = github.getOctokit(token)

  if (added < deleted) {
    octokit.rest.issues.createComment({
        issue_number: pr_payload.number,
        owner: github.context.repo.owner,
        repo: github.context.repo.repo,
        body: "🎉 🏆 This PR deletes more code than it adds! 🏆 🎉"
    })
  }

} catch (error) {
  core.setFailed(error.message);
}