JavaScript If Else & Switch

Conditional Logic (If-Else)

In programming, we often need to make decisions. Conditional logic allows a program to execute different pieces of code depending on whether a condition is true or false.

The "If" Statement

This is like saying: "If it's raining, take an umbrella." If the condition is True, the code inside the block runs. If it's False, it is skipped.

The "Else" Statement

This is the backup plan: "If it's raining, take an umbrella. Otherwise (Else), wear sunglasses."

The "Else If" (Elif) Ladder

When you have more than two options: 1. If score > 90: Grade A 2. Else If score > 80: Grade B 3. Else: Grade C

Logic First

Every conditional statement ultimately boils down to a Boolean value (True or False).

If, Else If, Else

if (time < 10) {
  greeting = "Good morning";
} else if (time < 20) {
  greeting = "Good day";
} else {
  greeting = "Good evening";
}

Switch Statement

The switch statement is used to perform different actions based on different conditions.

switch(new Date().getDay()) {
  case 0:
    day = "Sunday";
    break;
  case 1:
    day = "Monday";
    break;
  case 2:
     day = "Tuesday";
    break;
  case 3:
    day = "Wednesday";
    break;
  case 4:
    day = "Thursday";
    break;
  case 5:
    day = "Friday";
    break;
  case 6:
    day = "Saturday";
}

Strict Comparison

Switch cases use strict comparison (===). The values must be of the same type to match.

Break is Important

If you omit the break statement, the next case will be executed even if the evaluation does not match the case.