JavaScript 関数を使用して数学的な計算と論理的判断を実行します。

function add(a, b) {
  return a + b;
}

console.log(add(5, 3));  // 输出结果：8

function subtract(a, b) {
  return a - b;
}

console.log(subtract(5, 3));  // 输出结果：2

function multiply(a, b) {
  return a * b;
}

console.log(multiply(5, 3));  // 输出结果：15

function divide(a, b) {
  return a / b;
}

console.log(divide(6, 3));  // 输出结果：2

function checkNumber(number) {
  if (number > 0) {
    console.log("The number is positive.");
  } else if (number < 0) {
    console.log("The number is negative.");
  } else {
    console.log("The number is zero.");
  }
}

checkNumber(5);  // 输出结果：The number is positive.
checkNumber(-3); // 输出结果：The number is negative.
checkNumber(0);  // 输出结果：The number is zero.

function checkAge(age) {
  if (age >= 18 && age <= 60) {
    console.log("You are an adult.");
  } else if (age < 18 || age > 60) {
    console.log("You are not an adult.");
  }
}

checkAge(25);  // 输出结果：You are an adult.
checkAge(15);  // 输出结果：You are not an adult.
checkAge(65);  // 输出结果：You are not an adult.