index.js

import fetch from "node-fetch";
const { Octokit } = require("@octokit/core");
const core = require('@actions/core');

function findEmailCommitAPI(apiData) {

  const emailPosition = apiData.indexOf("\"email\":\"");

  if (emailPosition < 0) {
    return null;
  }

  const email = apiData.substring((emailPosition + 9), (emailPosition + 9 + (apiData.substring(emailPosition + 9).indexOf('\"'))));

  //if found a bot email, continue searching
  if (email.indexOf("users.noreply.github.com") >= 0) {
    return findEmailCommitAPI(apiData.substring(emailPosition + 9));
  }
  else {
    return email;
  }
}

try {
  //inputs defined in action metadata file
  const usernameForEmail = core.getInput('github-username');
  const token = core.getInput('token');

  console.log(`[*] Getting ${usernameForEmail}\'s GitHub email`);

  //attempt to use auth token to get email via accessing the user's API page
  let userAPIData = null;
  try {
    const octokit = new Octokit({ auth: `${token}` });
    userAPIData = await octokit.request(`GET /users/${usernameForEmail}`, {});
  } catch (error) {
    console.log("[!] " + error.message);
  }

  // Extract the email if the user's API was accessed successfully
  let emailUserpage = null;
  if (userAPIData != null && userAPIData.data != null && userAPIData.data.email != null &&  userAPIData.data.email != "") {
    emailUserpage = userAPIData.data.email;
  }

  //email not found on user's API page or failed to authenticate with token, fallback to old method to attempt email retrieval
  if (emailUserpage == null) {

    console.log(`[*] Falling back to old API retrieval method`);

    //fetch user's public events page
    fetch(`https://api.github.com/users/${usernameForEmail}/events/public`)
    .then(function(response) {

      // When the page is loaded convert it to text
      return response.text()
    })
    .then((apiData) => {

      const emailEventsPage = findEmailCommitAPI(apiData);

      if (emailEventsPage == null) {
        throw Error('[!!!] Could not find email in API Data');
      }

      console.log(`[*] Found ${usernameForEmail}\'s email: ${emailEventsPage}`)
      core.setOutput("email", emailEventsPage);
    })
    .catch((error) => {
      core.setFailed(error.message);
    });
  }
  else {
    console.log(`[*] Found ${usernameForEmail}\'s email: ${emailUserpage}`)
    core.setOutput("email", emailUserpage);
  }

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