Your friend just reinvented callback hell, but with extra steps. Instead of using a simple await sleep(1000) or even setTimeout , they decided to create the world's longest promise chain that looks like it's trying to reach the bottom of the Mariana Trench. The beautiful irony here is that promises were literally invented to avoid this kind of nesting nightmare. It's like someone handed them a ladder and they chose to stack chairs instead. Each .then() is probably just wrapping another promise that resolves after a delay, creating this magnificent stairway to callback heaven. Fun fact: This code probably has more indentation levels than the JavaScript spec has pages. The real kicker? A simple utility function like const sleep = ms => new Promise(resolve => setTimeout(resolve, ms)) would've saved them from this horizontal scroll of shame. But hey, at least they're consistent with their suffering!