fakeBrowser.js

gistfile1.txt

function fakeBrowser(initial) {
  const functionsToRun = [initial];

  const fakeWindow = {
    addCallback: function(fn) {
      functionsToRun.push(fn)
    }
  }

  while(functionsToRun.length > 0) {
    const nextFn = functionsToRun.shift();
    nextFn(fakeWindow)
  }
}

fakeBrowser(function(window) {
  console.log("Hi!")
  window.addCallback(function() {
    console.log("Hey!")
  });
})