# Control Flow in JavaScript

In this article, we learn about the control flow in the programming , why it exists and what are the different ways with which we can handle the control flow of the program.

## What is Control Flow?

**Control flow** refers to the **order in which a program executes its instructions**.

Normally, JavaScript executes code **line by line from top to bottom**. But in many situations, we need the program to **make decisions** and run different code based on conditions.

This is where **control flow statements** come into play.

### Real-Life Example

Imagine deciding what to wear:

```plaintext
If it is raining → take an umbrella
Else → wear sunglasses
```

### `if` statement

The `if` statement is used when we want to execute code **only if a condition is true**.

### Syntax

```javascript
if (condition) {
  // code runs if condition is true
}
```

### Example

```javascript
let age = 20;

if (age >= 18) {
  console.log("You can vote");
}
```

### `if...else` Statement

Sometimes we want to run **one block of code if the condition is true** and **another block if it is false**.

### Syntax

```plaintext
if (condition) {
  // runs if condition is true
} else {
  // runs if condition is false
}
```

```javascript
let age = 16;

if (age >= 18) {
  console.log("You can vote");
} else {
  console.log("You are too young to vote");
}
```

### `else if` Ladder

When we need to check **multiple conditions**, we use `else if`.

### Syntax

```plaintext
if (condition1) {
  // code
} else if (condition2) {
  // code
} else {
  // default code
}
```

```javascript
let marks = 75;

if (marks >= 90) {
  console.log("Grade A");
} else if (marks >= 70) {
  console.log("Grade B");
} else if (marks >= 50) {
  console.log("Grade C");
} else {
  console.log("Fail");
}
```

### `switch` Statement

The `switch` statement is used when we want to **compare one value against multiple possible options**.

### Syntax

```plaintext
switch (expression) {
  case value1:
    // code
    break;

  case value2:
    // code
    break;

  default:
    // code
}
```

```javascript
let 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("Invalid day");
}
```

### `break` Statement

The `break` statement **stops the switch execution**.

Without `break`, JavaScript continues executing the next cases.

Example without break:

```javascript
let day = 1;

switch (day) {
  case 1:
    console.log("Monday");

  case 2:
    console.log("Tuesday");
}

// without break
// o/p will be

// Monday
// Tuesday
```

### When to Use `switch` vs `if-else`

![](https://cdn.hashnode.com/uploads/covers/63cbeb71587fc59d3cd75412/2a4f4615-c5e8-4437-9025-8ccca37a5e01.png align="center")

### Conclusion

Control flow is an essential part of programming because it allows our programs to **make decisions based on conditions**.