条件（三元）运算符

function getFee(isMember) {
  return isMember ? "$2.00" : "$10.00";
}

console.log(getFee(true));
// Expected output: "$2.00"

console.log(getFee(false));
// Expected output: "$10.00"

console.log(getFee(null));
// Expected output: "$10.00"

condition ? exprIfTrue : exprIfFalse

const age = 26;
const beverage = age >= 21 ? "Beer" : "Juice";
console.log(beverage); // "Beer"

const greeting = (person) => {
  const name = person ? person.name : "stranger";
  return `Howdy, ${name}`;
};

console.log(greeting({ name: "Alice" })); // "Howdy, Alice"
console.log(greeting(null)); // "Howdy, stranger"

function example() {
  return condition1
    ? value1
    : condition2
      ? value2
      : condition3
        ? value3
        : value4;
}

function example() {
  if (condition1) {
    return value1;
  } else if (condition2) {
    return value2;
  } else if (condition3) {
    return value3;
  } else {
    return value4;
  }
}