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Examples

Armstrong Number in JavaScript (6 Programs)

An Armstrong number (also known as a narcissistic number) is a number that is equal to the sum of its own digits raised to the power of the number of digits. For example:

  • 153 is an Armstrong number because

  • 9474 is an Armstrong number because

This concept is commonly used in programming to demonstrate loops, conditions, and mathematical operations. In this tutorial, we will explore how to implement programs to check the Armstrong number in JavaScript. Whether you're writing an Armstrong number in js for a single number or a range, this guide has all the examples.

Armstrong Number in JavaScript Using for Loop

This program checks whether a given number is an Armstrong number using a for loop.

Code

function isArmstrongNumber(number) {
    const digits = number.toString().split("").map(Number);
    const power = digits.length;
    let sum = 0;

    for (let i = 0; i < digits.length; i++) {
        sum += Math.pow(digits[i], power);
    }

    return sum === number;
}

// Test the function
const num = 153;
console.log(`${num} is ${isArmstrongNumber(num) ? "an Armstrong" : "not an Armstrong"} number.`);

Output

153 is an Armstrong number.

Armstrong Number in JavaScript Using Function

This version encapsulates the logic in a reusable function.

Code

function checkArmstrongNumber(number) {
    let sum = 0;
    let temp = number;
    const power = number.toString().length;

    while (temp > 0) {
        const digit = temp % 10;
        sum += Math.pow(digit, power);
        temp = Math.floor(temp / 10);
    }

    return sum === number;
}

// Test the function
const testNum = 9474;
console.log(`${testNum} is ${checkArmstrongNumber(testNum) ? "an Armstrong" : "not an Armstrong"} number.`);

Output

9474 is an Armstrong number.

Armstrong Number Program in JavaScript Using while Loop

This program demonstrates how to check if a number is an Armstrong number using a while loop for processing its digits.

Code

function isArmstrongUsingWhile(number) {
    let sum = 0;
    let temp = number;
    const power = number.toString().length;

    while (temp > 0) {
        const digit = temp % 10;
        sum += Math.pow(digit, power);
        temp = Math.floor(temp / 10);
    }

    return sum === number;
}

// Test the function
const num2 = 370;
console.log(`${num2} is ${isArmstrongUsingWhile(num2) ? "an Armstrong" : "not an Armstrong"} number.`);

Output

370 is an Armstrong number.

Armstrong Number in JS Using toString and split Methods

This program uses the toString method to convert a number to a string and the split method to break it into individual digits for processing.

Code

function isArmstrongUsingSplit(number) {
    const digits = number.toString().split("").map(Number);
    const power = digits.length;
    const sum = digits.reduce((acc, digit) => acc + Math.pow(digit, power), 0);

    return sum === number;
}

// Test the function
const num3 = 407;
console.log(`${num3} is ${isArmstrongUsingSplit(num3) ? "an Armstrong" : "not an Armstrong"} number.`);

Output

407 is an Armstrong number.

Armstrong Number in JS Using Array.from Method

This method converts the number into an array of digits using Array.from for easier manipulation and calculation.

Code

function isArmstrongUsingArrayFrom(number) {
    const digits = Array.from(String(number), Number);
    const power = digits.length;
    const sum = digits.reduce((acc, digit) => acc + Math.pow(digit, power), 0);

    return sum === number;
}

// Test the function
const num4 = 9474;
console.log(`${num4} is ${isArmstrongUsingArrayFrom(num4) ? "an Armstrong" : "not an Armstrong"} number.`);

Output

9474 is an Armstrong number.

Armstrong Number in JS Using Array.reduce Method

This approach leverages the reduce method to compute the sum of digits raised to the power of the number of digits in a concise way.

Code

function isArmstrongUsingReduce(number) {
    const digits = number.toString().split("").map(Number);
    const power = digits.length;
    return digits.reduce((acc, digit) => acc + Math.pow(digit, power), 0) === number;
}

// Test the function
const num5 = 153;
console.log(`${num5} is ${isArmstrongUsingReduce(num5) ? "an Armstrong" : "not an Armstrong"} number.`);

Output

153 is an Armstrong number.

Armstrong Number in JavaScript for a Range of Numbers

This program finds and lists all Armstrong numbers within a given range by iterating through the range and checking each number.

Code

function findArmstrongNumbersInRange(start, end) {
    const armstrongNumbers = [];

    for (let i = start; i <= end; i++) {
        if (isArmstrongNumber(i)) {
            armstrongNumbers.push(i);
        }
    }

    return armstrongNumbers;
}

// Test the function
const startRange = 100;
const endRange = 999;
console.log(`Armstrong numbers between ${startRange} and ${endRange}:`, findArmstrongNumbersInRange(startRange, endRange));

Output

Armstrong numbers between 100 and 999: [153, 370, 371, 407]

Explanation

Concepts Used in Above Programs

A. Iteration

for and while loops are used to process digits of the number and iterate through ranges.

B. Mathematical Operations

Operations like Math.pow and % are used to calculate powers and extract digits.

C. Array and String Manipulation

Numbers are converted to strings and split into digits for easier processing in some examples.

D. Functions

Reusable functions improve code readability and reusability for checking Armstrong numbers.