associativity.js

let promise = Promise.resolve(1)

let nestedPromise1 = (x) => Promise.resolve(x * 2)
let nestedPromise2 = (x) => Promise.resolve(x + 6)

const firstNestingResult = await promise.then(nestedPromise1).then(nestedPromise2);
const secondNestingResult = await promise.then((x) => nestedPromise1(x).then(nestedPromise2));

console.log(firstNestingResult == secondNestingResult);
// Should log as true ✅