🎮 JavaScript if / switch トレーナー

1. 偶数・奇数ゲーム

function checkEvenOdd() {
  let num = document.getElementById("numberInput").value;
  let result = document.getElementById("result");

  if (num === "") {
    result.textContent = "⚠️ 数字を入力してください";
  } else if (num % 2 === 0) {
    result.textContent = "✅ 偶数です！";
  } else {
    result.textContent = "🎯 奇数です！";
  }
}
    

2. 曜日あてクイズ

function checkDay() {
  let day = Number(document.getElementById("dayInput").value);
  let output = document.getElementById("dayResult");

  switch (day) {
    case 1: output.textContent = "📅 月曜日"; break;
    case 2: output.textContent = "📅 火曜日"; break;
    case 3: output.textContent = "📅 水曜日"; break;
    case 4: output.textContent = "📅 木曜日"; break;
    case 5: output.textContent = "📅 金曜日"; break;
    case 6: output.textContent = "🎉 土曜日"; break;
    case 7: output.textContent = "🎉 日曜日"; break;
    default: output.textContent = "❌ 1〜7を入力してください";
  }
}
    

3. 合格チェック

function checkScore() {
  let score = document.getElementById("scoreInput").value;
  let result = document.getElementById("scoreResult");

  if (score === "") {
    result.textContent = "⚠️ 点数を入力してください";
  } else if (score >= 60) {
    result.textContent = "🎉 合格です！";
  } else {
    result.textContent = "💪 不合格";
  }
}
    

4. 正・負・ゼロチェック

function checkSign() {
  let num = document.getElementById("signInput").value;
  let result = document.getElementById("signResult");

  if (num > 0) {
    result.textContent = "➕ 正の数です";
  } else if (num < 0) {
    result.textContent = "➖ 負の数です";
  } else {
    result.textContent = "⭕ ゼロです";
  }
}
    

5. 年齢判定

function checkAge() {
  let age = document.getElementById("ageInput").value;
  let result = document.getElementById("ageResult");

  if (age >= 18) {
    result.textContent = "🧑 大人です";
  } else {
    result.textContent = "👶 子供です";
  }
}
    

6. 月あてゲーム

function checkMonth() {
  let month = Number(document.getElementById("monthInput").value);
  let result = document.getElementById("monthResult");

  switch (month) {
    case 1: result.textContent = "❄️ 1月"; break;
    case 2: result.textContent = "❄️ 2月"; break;
    case 3: result.textContent = "🌸 3月"; break;
    case 4: result.textContent = "🌸 4月"; break;
    case 5: result.textContent = "🌿 5月"; break;
    default: result.textContent = "❓ 未対応の月です";
  }
}