JavaScript notes

All notes

• let vs. var vs. const

  How the three declarations differ in scope, reassignment, hoisting, and everyday use.

• Closures

  Lexical scope, retained state, practical patterns, and common traps.

• Currying

  Closures, partial application, useful examples, and tradeoffs.

• bind, call, and apply

  Control this and pass arguments with JavaScript's function methods.

• map, filter, and reduce

  Mental models, examples, and mistakes to avoid when transforming arrays.

• Callbacks, Promises, and async/await

  Three ways to handle work that finishes later.

• The event loop

  The call stack, task queue, microtask queue, timers, and async/await.