1// 1. Declaration — create a variable or function
2let count = 0;
3const MAX = 100;
4function add(a, b) {
5  return a + b;
6}
7
8// 2. Expression Statement — do something with a value
9console.log('Hello!');
10count = count + 1;
11count++;
12
13// 3. Control Flow — decide what to run
14if (count > 0) {
15  console.log('Count is positive');
16} else {
17  console.log('Count is zero');
18}
19
20for (let i = 0; i < 3; i++) {
21  console.log('Loop:', i);
22}
23
24// 4. Block — group statements together
25{
26  let temp = 42;     // only lives inside this block
27  console.log('temp is:', temp);
28}
29// console.log(temp); // ERROR — temp doesn't exist here
30
31console.log(add(5, 7)); // 12

1// ✅ With semicolons — clear and safe
2const a = 5;
3const b = 10;
4console.log('Sum:', a + b);
5
6// ✅ Without semicolons — also works in most cases
7const x = 5
8const y = 10
9console.log('Total:', x + y)
10
11// Multiple statements on one line (not recommended)
12let p = 1; let q = 2; console.log(p + q);
13
14// do...while ALWAYS needs a semicolon at the end
15let n = 0;
16do {
17  n++;
18} while (n < 3);
19console.log('n =', n); // 3

1// ASI adds ; after each of these lines — works fine
2let a = 1
3let b = 2
4console.log(a + b)  // 3
5
6// Method chaining — ASI does NOT add ; here (correct!)
7// because the next line continues the expression
8const result = [10, 20, 30]
9  .find(x => x > 15)
10console.log(result) // 20
11
12// ASI always adds ; before a closing }
13function test() {
14  return 42   // ; added here by ASI
15}
16console.log(test()) // 42

1// ── TRAP 1: return on its own line ───────────────────────
2// JavaScript adds ; right after return
3// So the function returns undefined — not the object!
4
5function getUser() {
6  return         // ; added here by ASI ← BUG!
7  {
8    name: 'Alice'
9  }
10}
11console.log('WRONG:', getUser()) // undefined — not { name: 'Alice' }
12
13// FIX: put { on the same line as return
14function getUserFixed() {
15  return {       // no ; added here — safe
16    name: 'Alice'
17  }
18}
19console.log('FIXED:', getUserFixed()) // { name: 'Alice' }
20
21// ── TRAP 2: Array on the next line ───────────────────────
22// JavaScript thinks the [ continues the line above it
23// So it reads: const x = 1[1,2,3].forEach(...) ← TypeError!
24
25// WRONG (uncomment to see the error):
26// const x = 1
27// [1, 2, 3].forEach(n => console.log(n))
28
29// FIX: add a semicolon
30const x = 1;
31[1, 2, 3].forEach(n => console.log('item:', n));
32
33// ── TRAP 3: Function call on the next line ────────────────
34// JavaScript might think () calls the result of the line above
35// WRONG (uncomment to see):
36// const fn = () => 42
37// (function() { console.log('hello') })()
38
39// FIX: add a semicolon after the first line
40const fn = () => 42;
41(function() { console.log('IIFE runs safely'); })();

1// ✅ One statement per line — always
2const firstName = 'Alice';
3const lastName = 'Smith';
4const fullName = firstName + ' ' + lastName;
5console.log(fullName);
6
7// ✅ Always use { } for if/else — even for one line
8const score = 85;
9
10// ❌ Bad — no braces, easy to break later
11// if (score >= 90) console.log('A');
12
13// ✅ Good — braces make it safe and clear
14if (score >= 90) {
15  console.log('A');
16} else if (score >= 80) {
17  console.log('B');
18} else {
19  console.log('C or below');
20}
21
22// ✅ Always put { on the same line as return
23function getConfig() {
24  return {          // ← { here, not on the next line
25    theme: 'dark',
26    lang: 'en'
27  };
28}
29console.log(getConfig());