zone-timeout.js

var zoneA = Zone.current.fork({name: 'zoneA'});

function callback() {
  // Javascript engine context 2
  // Zone Context: zoneA
  
  // we can access the async execution context by call Zone.current
  console.log('ctx', Zone.current.name); // will be zoneA 
}

window.onload = zoneA.wrap(function() {
  // Javascript engine context 1
  // Zone Context: zoneA
  console.log('ctx', Zone.current.name); // will be zoneA 
  setTimeout(zoneA.wrap(callback), 100);
});