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<html>
  <head>
    <title>promise vs mutationobserver vs setImmediate vs setTimeout</title>
  </head>
  <body>
    <h1>promise vs mutationobserver vs setImmediate vs setTimeout</h1>
    <pre id="display"></pre>
    <script>
      (function () {
        function log(str) {
          display.innerHTML += str + '\n'
        }

        log('first')

        setTimeout(() => log('timeout'), 0)
        Promise.resolve().then(() => log('promise1')).then(() => log('promise2'))

        log('last')

      })()
    </script>
  </body>
</html>