Important Word
・Call Stack
・Task Queue(Callback Queue)
・Microtask Queue
1️⃣ check Call Stack → clear Call Stack
↓ if Call Stack is clear
2️⃣ check Task Queue → clear Task Queue
↓ if Task Queue is clear
3️⃣ check Microtask Queue → clear Microtask Queue
↓ if Microtask Queue is clear
go back to Call Stack and loop again. 1️⃣ → 2️⃣ → 3️⃣