TypeScript - If...else Statement

Introduction

The if...else statement is used to execute one block of code if a condition is true, and another block of code if the condition is false. It helps in controlling the flow of the program based on conditions.

Syntax:

if (condition) {
  // Code to execute if the condition is true
} else {
  // Code to execute if the condition is false
}

• The condition is an expression that evaluates to either true or false.
• If the condition is true, the code inside the if block is executed.
• If the condition is false, the code inside the else block is executed.

Example 1: Simple If-else

let number = 10;
 
if (number > 5) {
  console.log("Number is greater than 5.");
} else {
  console.log("Number is less than or equal to 5.");
}

Output:

Number is greater than 5.

Example 2: If-else with Comparison Operators

let age = 20;
 
if (age >= 18) {
  console.log("You are an adult.");
} else {
  console.log("You are a minor.");
}

Output:

You are an adult.

Example 3: If-else with Boolean Expression

let isRaining = false;
 
if (isRaining) {
  console.log("Don't forget your umbrella!");
} else {
  console.log("You can leave your umbrella at home.");
}

Output:

You can leave your umbrella at home.

Conclusion

The if...else statement is a fundamental control structure in TypeScript that allows you to execute different blocks of code depending on the truthiness of a condition. It is used in almost all programming scenarios where a decision needs to be made based on certain conditions.