domains.js

let domain = require('domain');

let fallbackCrumbs = [];

function getCrumbs() {
  if (domain.active) {
    let rv = domain.active.crumbs = domain.active.crumbs || [];
    return rv;
  }
  return fallbackCrumbs;
}

function addCrumb(crumb) {
  getCrumbs().push(crumb);
}

function showCrumbs(where) {
  console.log(`crumbs from ${where}: ${getCrumbs().join('; ')}`);
}

let d = domain.create();
d.enter();
  addCrumb('inner foo');
  setTimeout(() => {
    addCrumb('inner bar');
    Promise.resolve(42).then(() => {
      showCrumbs('inner');
    });
  }, 100);
d.exit();

addCrumb('outer foo');
showCrumbs('outer');