JavaScript Event Loop

Interactive visualization of the JavaScript runtime: Call Stack, Web APIs, Task Queue, and Microtask Queue.

Speed

Call Stack

0
Empty

Microtask Queue

0
Empty

Render (rAF)

0
Empty

Timers

0
Empty

I/O

0
Empty

Idle

0
Empty

Execution Statistics

Call Stack: 0
Microtasks: 0
Macrotasks: 0
Timers: 0
I/O: 0
Render: 0
Idle: 0

Current Phase

Waiting for tasks

The animation simulates: placing synchronous code on the Call Stack, scheduling timers and network requests in Web APIs, prioritizing Microtasks (Promise.then) over macrotasks (setTimeout) when the Call Stack is empty, and moving callbacks to the Stack.