How is the management of function execution order implemented in the Node.js environment?

In Node.js, the execution order of functions is managed by the event loop and task queues. The main mechanisms are:

• Call Stack — where functions are placed for execution.
• Event Loop — monitors the call stack and task queues to determine what to execute next.
• Task Queues:
  • Microtasks (e.g., promises) are executed immediately after the current operation, before moving to the next phase of the event loop.
  • Macrotasks (e.g., setTimeout, I/O operations) are executed in the event queues.

Thus, asynchronous functions, callbacks, and promises allow managing execution order by deferring code execution to the appropriate queues. For example, promises are always executed before setTimeout with zero delay.

Example:

console.log('Start');
setTimeout(() => console.log('Timeout'), 0);
Promise.resolve().then(() => console.log('Promise'));
console.log('End');
// Output will be:
// Start
// End
// Promise
// Timeout