Ok, so it is opposite in nodejs? There's a single JS thread but as soon as it performs any async IO ( which is the only IO that one should be performing in node ), that IO creates a thread servicing that IO request. In addition to that, if one is crazy enough to run long computational operations there's setTimeout(), setImmediate() and process.nextTick() and friends.

Though I would say it doing any real compute work inline rather than farming it out to workers is a boneheaded idea regardless of the language used.