I just published one of the deepest articles I’ve written on JavaScript internals.

Topic:

“JavaScript Is Single-Threaded… So Why Do Race Conditions Exist?”

Most developers hear:

“JavaScript is single-threaded.”

Then naturally assume:

no concurrency

no synchronization issues

no race conditions

But modern JavaScript systems constantly suffer from:

stale React state

async timing bugs

API overwrites

websocket ordering issues

cache corruption

inconsistent backend state

Why?

Because JavaScript concurrency is not really about threads.

It’s about asynchronous operations overlapping across time.

And once you begin understanding:

Event Loop internals

Promise scheduling

Microtasks vs Macrotasks

async/await execution flow

Node.js Event Loop phases

libuv architecture

process.nextTick()

Worker Threads

JavaScript suddenly stops feeling “magical.”

It starts feeling predictable.

One realization changed how I think about engineering:

Senior software engineering is mostly about execution order…