boa/index.js

// Note that a dynamic `import` statement here is required due to
// webpack/webpack#6615, but in theory `import { greet } from './pkg/hello_world';`
// will work here one day as well!
const rust = import("./pkg/boa");

rust.then(m => {
  window.evaluate = m.evaluate;
  let button = document.querySelector("button");
  button.addEventListener("click", clickHandler);
});

function clickHandler(evt) {
  let text = document.querySelector("textarea").value;
  let p = document.querySelector("p.output");
  let t0 = performance.now();
  let result = window.evaluate(text);
  let t1 = performance.now();
  p.textContent = `${t1 - t0}ms: ${result}`;
  console.log(result);
}