setup-job.js

import * as core from '@actions/core';
import * as github from '@actions/github';
import { exec } from 'node:child_process';

async function run() {
  try {
    const context = github.context;
    const eventName = context.eventName;
    let prNumber;
    if(eventName == 'pull_request') {
      prNumber = context.payload.number;
    } else if(eventName == 'push') {
      const message = context.payload.head_commit.message.split('\n')[0];
      const commitMessageParts = message.split(' ');
      prNumber = commitMessageParts[3].split('#')[1];
    } else {
      core.setFailed(`Unsupported event: ${eventName}`);
      return;
    }
    exec(`echo "REG_PR_NO=${prNumber}" >> $GITHUB_ENV`);
  } catch (error) {
    core.setFailed(error.message);
    return;
  }
}

await run();