Pure JS event loop implementation with only timers working

naive-event-loop.js

// timer.js

function main(global) {
  global.mySetTimeout(function () {
    console.log("500ms");
  }, 500);

  global.mySetTimeout(function () {
    console.log("100ms");
  }, 100);

  global.mySetTimeout(function () {
    console.log("300ms begin");
    global.mySetTimeout(function () {
      console.log("300ms + 0m");
    }, 0);
    global.nextTick = function () {
      console.log("nextTick");
    };
    console.log("300ms end");
  }, 300);

  global.mySetTimeout(function () {
    console.log("1000ms");
    global.exit();
  }, 1000);
}

// timer.cpp

// platform code
function eventLoop(main) {
  let exitFlag = false;
  let timers = [];

  const global = {
    mySetTimeout(cb, delay) {
      timers.push({
        callback: cb,
        dueDate: Date.now() + delay,
      });
      // …
    },

    exit() {
      exitFlag = true;
      throw "special"; // magic
    },
  };

  main(global);

  while (true) {
    if (exitFlag == true) {
      break;
    }

    const nextTimers = [];
    for (const { callback, dueDate } of timers) {
      if (dueDate <= Date.now()) {
        try {
          // enter the JS engine
          callback();
          // JS engine done with this portion of work
          if (global.nextTick) {
            // promises then() and catch() to be executed here
            // kinda microtasks
            global.nextTick();
            global.nextTick = undefined;
          }
          // check promises
        } catch {}
      } else {
        nextTimers.push({ callback, dueDate });
      }
    }
    timers = nextTimers;
  }
}

// glue-code.js.cpp

eventLoop(main);