Callbacks & Callback Hell

process.nextTick(() => callback());
setImmediate(() => callback());
setTimeout(() => callback(), 0);

setTimeout
setImmediate
process.nextTick
process.nextTick callbacks execute first due to Node.js's event loop phases: 1) process.nextTick queue is processed before the next event loop phase, 2) setTimeout(0) actually uses a 1ms minimum delay, 3) setImmediate executes in the check phase of the event loop, 4) This ordering is important for understanding callback execution timing, 5) process.nextTick is often used to ensure consistent async behavior while maintaining priority.
They execute in random order