# JavaScript Code

## Armstrong Number Program

In this tutorial, you are given a number. Write JavaScript program to check if given number is Armstrong number or not.

An n-digit number `abcd..` is said to be an Armstrong number if it obeys the following condition.

``abcd.. = pow(a,n) +  pow(b,n) + pow(c,n) + ...``

We write a function `isArmstrong()` that takes the given number as argument and return `true` if the number is Armstrong, or `false` otherwise.

Inside the function we compute the sum of powers (as in the above equation), and compare it with the original number.

To find the value of a raised to the power n, use Math.pow() function.

## Program

In the following program, given an n-digit number in `num`, check if it is an Armstrong number.

``````function isArmstrong(num) {
num = new String(num);
let n = num.length;
let result = 0;
//compute pow(a,n)+pow(b,n)+...
for ( let index = 0; index < num.length; index++ ) {
let digit = parseInt(num[index]);
result += Math.pow(digit, n);
}
//check if given number equals expansion
if( parseInt(num) == result ) {
return true;
} else {
return false;
}
}

let num = 153;
let result = isArmstrong(num);
console.log(`is \${num} an armstrong number? \${result}`);``````

We converted given number to string because we needed to work with individual digits, length, etc.