<div id="app"></div>
window.xs = xstream.default;
function main() {
  return xs
    .periodic(1000)
    .fold(prev => prev + 1, 0)
    .map(i => `Seconds elapsed: ${i}`);
}

function domDriver(text$) {
  text$.subscribe({
    next: str => {
      const elem = document.querySelector("#app");
      elem.textContent = str;
    }
  });
}

function logDriver(msg$) {
  msg$.subscribe({
    next: str => {
      console.log(str);
    }
  });
}
const sink = main();
domDriver(sink);
logDriver(sink);
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External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/xstream/11.7.0/xstream.min.js