Introduction

Control flow in programming determines the order in which statements are executed. Normally, code runs from top to bottom, but control flow statements allow the program to make decisions and execute different blocks of code based on conditions.

In JavaScript, common control flow statements include:

• if

• if-else

• else if

• switch

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1. What Control Flow Means in Programming

Control flow refers to how a program chooses which instructions to execute depending on conditions.

Real-Life Example

If it is raining → take an umbrella
Else → go outside normally.

Programming follows the same logic.

Example in JavaScript:

let isRaining = true;

if (isRaining) {
  console.log("Take an umbrella");
}

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2. The if Statement

The if statement executes a block of code only when the condition is true.

Syntax

if(condition){
   // code to run
}

Example

let age = 18;

if(age >= 18){
  console.log("You are eligible to vote");
}

If the condition is true, the message will be displayed.

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3. The if-else Statement

The if-else statement allows the program to choose between two possible actions.

Syntax

if(condition){
   // code if true
}else{
   // code if false
}

Example

let age = 16;

if(age >= 18){
  console.log("You can vote");
}else{
  console.log("You cannot vote yet");
}

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4. The else if Ladder

The else if ladder is used when multiple conditions need to be checked.

Syntax

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

Example (Marks Grading)

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");
}

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5. The switch Statement

The switch statement is used when a variable can have multiple specific values.

Syntax

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

   case value2:
      // code
      break;

   default:
      // default code
}

Example

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");
}

Role of break

The break statement stops the execution of the switch block.
Without break, the program continues to the next case.

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6. When to Use switch vs if-else

Feature	if-else	switch
Best for	Complex conditions	Fixed values
Conditions	Range conditions	Exact matches
Readability	Good for logic checks	Cleaner for many cases

Example

Use if-else for marks or age comparisons:

if(age > 18)

Use switch for menu or day selection:

switch(day)

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Conclusion

Control flow statements allow programs to make decisions and execute different instructions based on conditions.
Using statements like if, if-else, else-if, and switch, developers can create flexible and logical programs.

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