200+ JavaScript Programs for Beginners

Intro

Programming in JS was complicated until you appreciated this wonderful book.

Focus on the most important thing writing code, starting from the first program to the last will help you quickly increase your skills as a programmer and will give you the knowledge necessary to understand:

The flow of a program, the syntax, the direction, how it works, what Add keywords to your code, make great decisions, and much more.

This is a very essential guide with which you can learn to create more than... Once you have solved a certain number of programs, you will be able to develop yourself and turn your own ideas into a reality without even having to think about it.

1. Print Hello World

The Hello World program is a classic in programming and is often the first program written when learning a new programming language. In this case, the goal is to print the text string Hello, World! to the browser console.

console.log(Hello, World!);

2. Add Two Numbers

This program focuses on taking two numbers as input and then displaying their sum. It prompts the user to enter two numbers, adds them together, and prints the result.

let num1 = parseFloat(prompt(Enter the first number:));

let num2 = parseFloat(prompt(Enter the second number:));

if (!isNaN(num1) && !isNaN(num2)) {

let sum = num1 + num2;

console.log(`The sum of ${num1} and ${num2} is: ${sum}`);

} else {

console.log(Please enter valid numbers.);

}

3. Find the Square Root

This program prompts the user to enter a number and calculates its square root. It then displays the result, ensuring that the entered number is non-negative.

let inputNumber = parseFloat(prompt(Enter a non-negative number:));

if (!isNaN(inputNumber) && inputNumber >= 0) {

let squareRoot = Math.sqrt(inputNumber);

console.log(`The square root of ${inputNumber} is: ${squareRoot}`);

} else {

console.log(Please enter a valid non-negative number.);

}

4. Calculate the Area of a Triangle

This program prompts the user to enter the base and height of a triangle and calculates its area using the formula: Area=12×Base×HeightArea=21​×Base×Height. It then displays the calculated area.

let base = parseFloat(prompt(Enter the base of the triangle:));

let height = parseFloat(prompt(Enter the height of the triangle:));

if (!isNaN(base) && !isNaN(height) && base > 0 && height > 0) {

let area = 0.5 * base * height;

console.log(

`The area of the triangle with base ${base} and height ${height} is: ${area}`

);

} else {

console.log(Please enter valid positive numbers for base and height.);

}

5. Swap Two Variables

This program prompts the user to enter two variables and swaps their values. It then displays the variables before and after the swap.

let variable1 = prompt(Enter the first variable:);

let variable2 = prompt(Enter the second variable:);

console.log(

`Before swapping: Variable1 = ${variable1}, Variable2 = ${variable2}`

);

// Swapping the variables

let temp = variable1;

variable1 = variable2;

variable2 = temp;

console.log(

`After swapping: Variable1 = ${variable1}, Variable2 = ${variable2}`

);

6. Solve Quadratic Equation

This program solves a quadratic equation of the form ax^2 + bx + c = 0, where a, b, and c are coefficients. It uses the quadratic formula to find the roots of the equation.

// Prompt user for coefficients

let a = parseFloat(prompt(Enter the coefficient a:));

let b = parseFloat(prompt(Enter the coefficient b:));

let c = parseFloat(prompt(Enter the coefficient c:));

// Calculate the discriminant

let discriminant = b ** 2 - 4 * a * c;

// Check if roots are real

if (!isNaN(a) && !isNaN(b) && !isNaN(c)) {

if (discriminant > 0) {

let root1 = (-b + Math.sqrt(discriminant)) / (2 * a);

let root2 = (-b - Math.sqrt(discriminant)) / (2 * a);

console.log(

`The roots of the quadratic equation are: ${root1} and ${root2}`

);

} else if (discriminant === 0) {

let root = -b / (2 * a);

console.log(`The quadratic equation has a repeated root: ${root}`);

} else {

console.log(The quadratic equation has complex roots.);

}

} else {

console.log(Please enter valid numbers for coefficients.);

}

7. Convert Kilometers to Miles

This program prompts the user to enter a distance in kilometers and converts it to miles using the conversion factor: 1 kilometer is approximately equal to 0.621371 miles. It then displays the converted distance.

// Prompt user for distance in kilometers

let kilometers = parseFloat(prompt(Enter the distance in kilometers:));

// Conversion factor

const kilometersToMilesConversionFactor = 0.621371;

// Check if input is a valid number

if (!isNaN(kilometers)) {

// Convert kilometers to miles

let miles = kilometers * kilometersToMilesConversionFactor;

console.log(`${kilometers} kilometers is approximately ${miles} miles.`);

} else {

console.log(Please enter a valid number for the distance in kilometers.);

}

8. Convert Celsius to Fahrenheit

This program converts a temperature from Celsius to Fahrenheit using the formula: F = (C * 9/5) + 32, where F is the temperature in Fahrenheit and C is the temperature in Celsius.

// Prompt user for temperature in Celsius

let celsius = parseFloat(prompt(Enter the temperature in Celsius:));

// Check if input is a valid number

if (!isNaN(celsius)) {

// Convert Celsius to Fahrenheit

let fahrenheit = (celsius * 9) / 5 + 32;

console.log(

`${celsius} degrees Celsius is equal to ${fahrenheit} degrees Fahrenheit.`

);

} else {

console.log(Please enter a valid number for the temperature in Celsius.);

}

9. Generate a Random Number

This program generates a random number between a user-defined range. It prompts the user to enter the minimum and maximum values of the range, and then it displays the generated random number within that range.

// Prompt user for the range

let minRange = parseFloat(prompt(Enter the minimum value of the range:));

let maxRange = parseFloat(prompt(Enter the maximum value of the range:));

// Check if input is a valid number

if (!isNaN(minRange) && !isNaN(maxRange) && minRange < maxRange) {

// Generate a random number within the specified range

let randomNumber = Math.random() * (maxRange - minRange) + minRange;

console.log(

`A random number between ${minRange} and ${maxRange} is: ${randomNumber}`

);

} else {

console.log(

Please enter valid numbers, ensuring that the minimum value is less than the maximum value.

);

}

10. Check if a number is Positive, Negative, or Zero

This program prompts the user to enter a number and checks whether it is positive, negative, or zero. It then displays the result.

// Prompt user for a number

let number = parseFloat(prompt(Enter a number:));

// Check if input is a valid number

if (!isNaN(number)) {

// Check if the number is positive, negative, or zero

if (number > 0) {

console.log(`${number} is a positive number.`);

} else if (number < 0) {

console.log(`${number} is a negative number.`);

} else {

console.log(The entered number is zero.);

}

} else {

console.log(Please enter a valid number.);

}

11. Check if a Number is Odd or Even

This program prompts the user to enter a number and checks whether it is odd or even. It then displays the result.

// Prompt user for a number

let number = parseInt(prompt(Enter a number:));

// Check if input is a valid integer

if (!isNaN(number) && Number.isInteger(number)) {

// Check if the number is odd or even

if (number % 2 === 0) {

console.log(`${number} is an even number.`);

} else {

console.log(`${number} is an odd number.`);

}

} else {

console.log(Please enter a valid integer.);

}

12. Find the Largest Among Three Numbers

This program prompts the user to enter three numbers and determines and displays the largest among them.

// Prompt user for three numbers

let num1 = parseFloat(prompt(Enter the first number:));

let num2 = parseFloat(prompt(Enter the second number:));

let num3 = parseFloat(prompt(Enter the third number:));

// Check if inputs are valid numbers

if (!isNaN(num1) && !isNaN(num2) && !isNaN(num3)) {

// Find the largest among the three numbers

let largestNumber = Math.max(num1, num2, num3);

console.log(

`The largest number among ${num1}, ${num2}, and ${num3} is: ${largestNumber}`

);

} else {

console.log(Please enter valid numbers for all three inputs.);

}

13. Check Prime Number

This program prompts the user to enter a number and checks whether it is a prime number or not. It then displays the