Node.js Event Loop Visualizer
100% Client-Side - Local Browser ProcessingInteractive Phase Stepper
Inspect Call Stack, Timers, I/O Poll, and Check (setImmediate) phases with frame-by-frame execution control.
Microtask & nextTick Priority
Visualize how process.nextTick prioritizes over Promise microtasks before advancing to the next Event Loop phase.
100% Client-Side Sandbox
All AST parsing, queue orchestration, and simulation runs locally in your browser with zero server data transfer.
Understanding the Node.js Event Loop & Task Queues
The Node.js Event Loop manages asynchronous non-blocking I/O operations through structured execution phases:
- Call Stack Execution: Synchronous code runs first on the V8 engine call stack until the stack is completely empty.
- Ticks & Microtasks: process.nextTick callbacks drain first with highest priority, followed immediately by Promise microtasks.
- Timers Phase: Expired timer callbacks registered by setTimeout and setInterval are executed.
- Poll & Check Phases: I/O callbacks are retrieved in the Poll phase, followed by setImmediate callbacks in the Check phase.
Client-Side Event Loop Simulation
All code inspection and event loop stepping run in-browser:
Local AST Parsing: User scripts are parsed and evaluated inside browser JavaScript without sending code to remote servers.
Safe Sandbox: Sandboxed execution prevents memory leaks and guarantees full privacy.
Frequently Asked Questions
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