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## 1. `if`, `else if`, `else`

This is the **main** and most readable construct for branching code.

```javascript
const age = 20;

if (age >= 18) {
  console.log('Adult');
} else if (age >= 14) {
  console.log('Teenager');
} else {
  console.log('Child');
}
```

- `if` checks a condition
- `else if` adds additional checks
- `else` runs if all the previous ones did not match

> The condition inside `if` is converted to a **boolean value** (truthy/falsy).

---

## 2. The ternary operator `? :`

A short form for simple conditions.

```javascript
const age = 18;
const status = age >= 18 ? 'Adult' : 'Minor';

console.log(status); // "Adult"
```

Syntax:
`condition ? value_if_true : value_if_false`

You can nest several ternary operators (but be careful with readability):

```javascript
const age = 25;
const group =
  age < 13 ? 'child' :
  age < 20 ? 'teenager' :
  'adult';
```

---

## 3. The `switch` statement

Convenient when there are many variants of the same expression.

```javascript
const day = 3;

switch (day) {
  case 1:
    console.log('Monday');
    break;
  case 2:
    console.log('Tuesday');
    break;
  case 3:
    console.log('Wednesday');
    break;
  default:
    console.log('Unknown day');
}
```

- `break` prevents "falling through" into the next `case`
- `default` is the equivalent of `else`

You can use **grouping**:

```javascript
switch (day) {
  case 6:
  case 7:
    console.log('Day off');
    break;
  default:
    console.log('Workday');
}
```

---

## 4. The logical operators `&&`, `||`, `??`

Sometimes `if` can be **replaced** with logical shorthand.

### `&&`: "and" (runs the second operand if the first is true)

```javascript
const isAdmin = true;
isAdmin && console.log('Welcome, admin!');
```

> If `isAdmin === true`, `console.log` will run.

---

### `||`: "or" (returns the first truthy value)

```javascript
const userName = '' || 'Guest';
console.log(userName); // "Guest"
```

> Convenient for default values.

---

### `??`: "nullish coalescing" (only for `null` and `undefined`)

```javascript
const userInput = null;
const value = userInput ?? 'Default';
console.log(value); // "Default"
```

> Difference from `||`: it does not trigger on `0`, `''`, `false`.

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