⚡ JavaScript Lesson 03 — Loops

1. for Loop — အကြိမ်ရေ သိတဲ့ Loop

// for (start; condition; step)
for (let i = 0; i < 5; i++) {
  console.log(i)
}
// Output: 0, 1, 2, 3, 4

// Count down
for (let i = 10; i >= 0; i--) {
  console.log(i)
}

// Step by 2
for (let i = 0; i <= 10; i += 2) {
  console.log(i)  // 0, 2, 4, 6, 8, 10
}

2. while Loop — Condition စစ်ပြီး Loop

let count = 1
while (count <= 5) {
  console.log(`Count: ${count}`)
  count++         // မ++ရင် infinite loop!
}

// do...while — ရှေ့ဆုံး တစ်ကြိမ်ဆောင်ရွက်မယ်
let i = 10
do {
  console.log(i)
  i++
} while (i < 5)
// Output: 10 ← ပထမဆုံး run ပြီး condition စစ်

3. for...of & for...in

// for...of — Array iterate
const fruits = ["apple", "banana", "mango"]

for (const fruit of fruits) {
  console.log(fruit)
}
// apple
// banana
// mango

// String iterate လည်း ရ
for (const ch of "Hello") {
  console.log(ch) // H, e, l, l, o
}

// for...in — Object properties
const person = {
  name: "Ko Min",
  age: 25,
  city: "Yangon"
}

for (const key in person) {
  console.log(`${key}: ${person[key]}`)
}
// name: Ko Min
// age: 25
// city: Yangon

4. break & continue

// break — loop ကို ချက်ချင်း ရပ်တယ်
for (let i = 1; i <= 10; i++) {
  if (i === 6) break
  console.log(i)
}
// Output: 1, 2, 3, 4, 5

// continue — ဒီ iteration ကို skip ပြီး ဆက်
for (let i = 1; i <= 10; i++) {
  if (i % 2 === 0) continue  // skip even numbers
  console.log(i)
}
// Output: 1, 3, 5, 7, 9 (odd only)

5. Array forEach — Modern Loop

const numbers = [1, 2, 3, 4, 5]

// forEach — loop ဆောင်ရွက် (return မရ)
numbers.forEach(function(num) {
  console.log(num * 2)
})

// Arrow function version (shorter)
numbers.forEach(num => console.log(num * 2))

// With index
numbers.forEach((num, index) => {
  console.log(`[${index}] = ${num}`)
})

6. Real-world Example — Multiplication Table

function multiplyTable(n) {
  let result = ""
  for (let i = 1; i <= 10; i++) {
    result += `${n} × ${i} = ${n * i}\n`
  }
  return result
}
console.log(multiplyTable(5))

7. Classic: FizzBuzz

for (let i = 1; i <= 30; i++) {
  if (i % 15 === 0) {
    console.log("FizzBuzz")
  } else if (i % 3 === 0) {
    console.log("Fizz")
  } else if (i % 5 === 0) {
    console.log("Buzz")
  } else {
    console.log(i)
  }
}