Alternative funzionali — passare il contesto, closure, piccoli helper

Perché le alternative funzionali?

Funzione pura al posto di this

// Pure function: takes data as parameters
function fullName(user) {
  // no this; explicit inputs
  return user.first + " " + user.last;
}

const u = { first: "Ayla", last: "Kaya" };
console.log("fullName:", fullName(u));

Helper basato su una closure

// Closure: capture config and return a tiny helper
function makeGreeter(prefix) {
  // returns a function that remembers prefix
  return function (name) {
    return prefix + " " + name;
  };
}

const hi = makeGreeter("Hello");
console.log(hi("Ayla")); // "Hello Ayla"
console.log(hi("Mila")); // "Hello Mila"

Factory senza this

// Factory pattern: build an object with simple, pure-like methods
function makeCounter(start) {
  let value = Number.isFinite(start) ? start : 0;

  return {
    get: function () { return value; },        // read
    inc: function () { value = value + 1; }    // update (encapsulated)
  };
}

const c = makeCounter(2);
c.inc();
console.log("counter:", c.get()); // 3

Comporre piccoli helper

// Compose small helpers: map + filter as plain functions
function isAdult(user) { return user.age >= 18; }
function toLabel(user) { return user.name + " (" + user.age + ")"; }

const people = [
  { name: "Ayla", age: 18 },
  { name: "Mert", age: 16 },
  { name: "Lina", age: 21 }
];

const labels = people.filter(isAdult).map(toLabel);
console.log("labels:", labels);

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