learn/javascript
JavaScript Runtime Visualizer
Learn JavaScript by running code and watching call stack, execution contexts, lexical environment, and event loop behavior animate step-by-step.
JavaScript Concepts Lab
Type and run JavaScript to animate core runtime internals in real time.
Execution Context
See how global and function execution contexts are created and destroyed as JavaScript runs line-by-line.
Focus: Call stack • Execution context • Scope snapshot
Frame: 0/0
Call Stack
global()
Execution Context Stack
GlobalExecutionContext
Microtask Queue
empty
Task Queue
empty
Lexical Environment
No variables captured yet.
Source + Active Line
1const message = "hello";23function greet(name) {4 const local = "inside greet";5 return message + " " + name + " (" + local + ")";6}78console.log(greet("Ada"));
Console Output
No logs yet.