Making Decisions with JavaScript if, else if, and else

let age = 20;
if (age >= 18) {
  console.log("You can vote! 🗳️");
}

if (condition) {
  // code that runs ONLY when condition is true
}

let age = 15;
if (age >= 18) {
  console.log("You can vote! 🗳️");
  // skipped — condition was false}
  console.log("Program continues…");
  // ← this always runs

let age = 15;
if (age >= 18) {
  console.log("You can vote! 🗳️");
} else {
  console.log("Sorry — come back in a few years. 🕰️");
}

condition true? → if block runsage >= 18 condition false? → else block runs

let enteredPassword = "secret123";
let savedPassword = "secret123";
if (enteredPassword === savedPassword) {
  console.log("✅ Login successful! Welcome back.");
} else {
  console.log("❌ Wrong password. Try again.");
}

let score = 75;
if (score >= 90) {
  console.log("Grade: A 🏆");
} else if (score >= 75) {
  console.log("Grade: B 🎉");
  // ← this runs (75 >= 75 is true)
} else if (score >= 60) {
  console.log("Grade: C 👍");
  // never even checked!
} else {
  console.log("Grade: F — keep practicing! 💪");
}

score >= 90? → NO↓score >= 75? → YES → run this block → SKIP everything belowscore >= 60? →(never reached)else →(never reached)

let score = 95;
// ❌ WRONG ORDER — watch what happens:
if (score >= 60) {
  console.log("Grade: C 👍");
  // 95 >= 60 is TRUE → runs first!
} else if (score >= 90) {
  console.log("Grade: A 🏆");
  // never reached 😱
}// Output: "Grade: C" — a 95 scorer got a C!

let isLoggedIn = true;
let isAdmin = false;
if (isLoggedIn) {
  console.log("Welcome back! 👋");
  if (isAdmin) {
    console.log("🔑 Admin dashboard unlocked");
  } else {
    console.log("👤 Standard member area");
  }
} else {
  console.log("Please log in first 🔒");
}

Welcome back! 👋👤 Standard member area

// Nested version (2 levels deep)if (isLoggedIn) {  if (isAdmin) {    showDashboard();  }}
// Flattened with && — cleaner for simple cases ✅if (isLoggedIn && isAdmin) {  showDashboard();}

let age = 25;
let hasID = true;
let isWeekend = false;
// && — all must passif (age >= 18 && hasID) {  console.log("Entry allowed 🎟️");}
// || — any one passesif (isWeekend || age < 18) {  console.log("Discount ticket available! 🎫");}
// ! — flipped logicif (!hasID) {  console.log("Please bring your ID next time 🪪");}
// Mixed — use parentheses for clarity (Lesson 6's advice!)if ((age >= 18 && hasID) || isWeekend) {  console.log("Special entry rules apply ⭐");}

let temperature = 24;
// ❌ Never: if (18 <= temperature <= 30) — broken chaining!
if (temperature >= 18 && temperature <= 30) {
  console.log("Perfect weather! 🌤️");
  // ← runs
}

let age = 20;
// Ternary — great for ASSIGNING one of two values
let category =(age >= 18) ? "Adult ✅" : "Minor 🧒";
console.log(category);
// Adult ✅
// Same logic as if/else — 5 lines vs 1:
let category2;
if (age >= 18) {
  category2 = "Adult ✅";
} else {
  category2 = "Minor 🧒";
}

// 📊 Grade Calculator
let studentName = "Riya";
let score = 82;
let grade;
let message;
if (score >= 90) {
  grade = "A";
  message = "Outstanding! 🏆";
} else if (score >= 75) {
  grade = "B";
  message = "Great job! 🎉";
} else if (score >= 60) {
  grade = "C";
  message = "Good effort! 👍";
} else if (score >= 40) {
  grade = "D";
  message = "You passed — keep pushing! 📚";
} else {
  grade = "F";
  message = "Don't give up — practice makes progress! 💪";
}console.log(`Student: ${studentName}`);
console.log(`Score: ${score}/100`);
console.log(`Grade: ${grade}`);
console.log(message);
// Bonus decision — scholarship check (combining conditions!)
if (score >= 90 && grade === "A") {
  console.log("🎓 Scholarship eligible!");
}

Student: RiyaScore: 82/100Grade: BGreat job! 🎉