Else If Statement in TypeScript

In this tutorial, we will learn about else-if statements in TypeScript. We will cover the basics of conditional execution using if-else-if statements.

What is an Else-If statement

An else-if statement is a conditional statement that allows multiple conditions to be tested sequentially. It provides a way to execute different code blocks based on different conditions.

Syntax

The syntax for the else-if statement in TypeScript is:

if (condition1) {
    // Code block to execute if condition1 is true
} else if (condition2) {
    // Code block to execute if condition2 is true
} else {
    // Code block to execute if none of the conditions are true
}

The else-if statement evaluates the specified conditions in order. The first condition that is true will have its code block executed; if none of the conditions are true, the code block inside the else statement is executed.

Flowchart of Else-If Statement

Example 1: Checking if a Number is Positive, Negative, or Zero

  1. Declare a variable num.
  2. Assign a value to num.
  3. Use an if-else-if statement to check if num is positive, negative, or zero.
  4. Print a message indicating whether num is positive, negative, or zero.

TypeScript Program

let num: number = -5;
if (num > 0) {
    console.log(`${num} is positive.`);
} else if (num < 0) {
    console.log(`${num} is negative.`);
} else {
    console.log(`${num} is zero.`);
}

Output

-5 is negative.

Example 2: Checking the Grade of a Student

  1. Declare a variable marks.
  2. Assign a value to marks.
  3. Use an if-else-if statement to check the grade based on the marks.
  4. Print a message indicating the grade.

TypeScript Program

let marks: number = 85;
if (marks >= 90) {
    console.log('Grade: A');
} else if (marks >= 80) {
    console.log('Grade: B');
} else if (marks >= 70) {
    console.log('Grade: C');
} else if (marks >= 60) {
    console.log('Grade: D');
} else {
    console.log('Grade: F');
}

Output

Grade: B

Example 3: Checking the Temperature Range

  1. Declare a variable temperature.
  2. Assign a value to temperature.
  3. Use an if-else-if statement to check the range of the temperature.
  4. Print a message indicating the temperature range.

TypeScript Program

let temperature: number = 75.5;
if (temperature > 100) {
    console.log('It's extremely hot.');
} else if (temperature > 85) {
    console.log('It's hot.');
} else if (temperature > 60) {
    console.log('It's warm.');
} else if (temperature > 32) {
    console.log('It's cold.');
} else {
    console.log('It's freezing.');
}

Output

It's warm.