To implement a custom Promise, one must understand its fundamental behavior: it is a constructor that accepts a executor function (which receives resolve and reject callbacks). The state of a Promise transitions from pending to either fulfilled (resolved) or rejected, and the then method allows us t...
A Promise is a built-in JavaScript object introduced in ECMAScript 2015 that represents the eventual outcome of an asynchronous operation — either a resolved value or a reason for rejection. Each Promise instance transitions through exactly one of three mutually exclusive states: Pending: The initia...
Synchronous vs Asynchronous Execution Models In blocking (synchronous) execution, operations run sequentially. Each statement waits for the previous one to complete before executing. When encountering time-consuming I/O operations or network requests, the entire thread halts, creating performance bo...