func.js

// what is output?
const foo = () => {
  let a = (b = 10);
  a++;
  return a;
};

foo();

console.log(a);
console.log(b);

// output
function createIncrement() {
  let count = 0;

  function increment() {
    count++;
  }

  let message = `Count is ${count}`;
  function log() {
    console.log(message);
  }

  return [increment, log];
}

const [increment, log] = createIncrement();

increment();
increment();
increment();

log();

// Console sequence output?
function run() {
  const promise = new Promise((resolve) => {
    resolve("promise");
  });

  setTimeout(() => {
    console.log("setTimeout");
  });

  promise.then((res) => console.log(res));

  console.log("log");
}

run();

// How does the Javascript interprets the following code?
console.log(x);
var x = 100;

// Output
(function () {
  var a = (b = 5);
})();

console.log(b);