Learn Modern Javascript From Ground Zero Chapter 2 Grammar Types Declarations

Summary

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. Well-known symbols, Proxy and Reflect, the new using 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. Float precision, UTF-16 strings, template tags, Date pitfalls, the new Temporal API, and Intl formatting for any language. Every form of import and export, live bindings, dynamic import(), import.meta, JSON modules, and ESM vs CommonJS. Arrow functions, default and rest parameters, the rules that decide this, and closures, the idea behind private state.