Programming is basically giving instructions to a computer.
But sometimes the program needs to make decisions.

Just like real life.

Example:
If it’s raining → take an umbrella.
If not → just go outside.

This idea in programming is called control flow.

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What control flow means in programming

Control flow means deciding which part of the code runs and when.

Instead of running every line blindly, the program checks conditions and then chooses what to do next.

This is how programs become smart and interactive.

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The if statement

The if statement runs code only when a condition is true.

Example:

let age = 18;

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

Here the program checks the condition first.

If it’s true, the code inside runs.

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The if-else statement

Sometimes we need two possible outcomes.

Example:

let age = 16;

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

So the program chooses one path or the other.

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The else if ladder

When there are multiple conditions, we use else if.

Example:

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");
}

The program checks each condition one by one until one becomes true.

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The switch statement

switch is another way to handle multiple choices.

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");
}

Important thing: break stops the next cases from running.

Without break, the program continues to the next case.

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When to use switch vs if-else

Use if-else when:

• conditions involve ranges or comparisons

• logic is more flexible

Use switch when:

• checking one variable

• matching exact values

Both solve similar problems, but sometimes one is cleaner.

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Simple Assignment Examples

1. Check if a number is positive, negative, or zero

let num = -5;

if (num > 0) {
  console.log("Positive number");
} else if (num < 0) {
  console.log("Negative number");
} else {
  console.log("Zero");
}

Here I used if-else because we are comparing ranges (> 0, < 0).

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2. Print the day of the week using switch

let day = 2;

switch(day) {
  case 1:
    console.log("Monday");
    break;
  case 2:
    console.log("Tuesday");
    break;
  case 3:
    console.log("Wednesday");
    break;
  case 4:
    console.log("Thursday");
    break;
  case 5:
    console.log("Friday");
    break;
  case 6:
    console.log("Saturday");
    break;
  case 7:
    console.log("Sunday");
    break;
  default:
    console.log("Invalid day");
}

Here I used switch because we are checking exact values of a variable.