Learn Modern Javascript From Ground Zero Chapter 15 Metaprogramming Resource Management

Summary

Well-known symbols, Proxy and Reflect, the new using declaration for automatic cleanup, and how Why let and const replaced var, what hoisting and the temporal dead zone really are, and Optional chaining, nullish coalescing, destructuring and spread, and the == vs === question settled for good. Every form of import and export, live bindings, dynamic import(), import.meta, JSON modules, and ESM vs CommonJS. Map vs object, the new Set operations, Object.groupBy, getOrInsert, and weak collections that let memory go. Object literals, key order, hasOwn, property descriptors, enumerability, and the right way to copy objects. Watch this first: how every course here is built, and why it matches the way your brain