Vorzeitige Rückgaben und Guard Clauses

// Nested style without guard
function welcome(name) {
  if (name) {
    const message = "Hello, " + name + "!";
    console.log(message);
  } else {
    console.log("Name required");
  }
}

welcome("Ayla");
welcome("");

// Guard clause: return early for bad input
function welcomeSafe(name) {
  if (!name) {
    console.log("Name required");
    return;
  }
  const message = "Hello, " + name + "!";
  console.log(message);
}

welcomeSafe("Ayla");
welcomeSafe("");

// Multiple guard clauses keep each rule small
function divide(a, b) {
  if (typeof a !== "number" || typeof b !== "number") {
    console.log("Numbers only");
    return;
  }
  if (b === 0) {
    console.log("Cannot divide by zero");
    return;
  }
  const result = a / b;
  console.log("Result:", result);
}

divide(6, 3);
divide(6, 0);
divide("6", 3);

// Early returns reduce else blocks
function canVote(age) {
  if (typeof age !== "number") {
    return false;
  }
  if (age < 18) {
    return false;
  }
  return true;
}

console.log(canVote(20));
console.log(canVote(15));
console.log(canVote("20"));