A number is called Armstrong number if the following equation holds true for that number −
xy..z = x^n + y^n+.....+ z^n
Where, n denotes the number of digits in the number
For example − 370 is an Armstrong number because −
3^3 + 7^3 + 0^3 = 27 + 343 + 0 = 370
We are required to write a JavaScript function that takes in two numbers, a range, and returns all the numbers between them that are Armstrong numbers (including them, if they are Armstrong).
Example
Let’s write the code for this function −
const isArmstrong = number => {
let num = number;
const len = String(num).split("").length;
let res = 0;
while(num){
const last = num % 10;
res += Math.pow(last, len);
num = Math.floor(num / 10);
};
return res === number;
};
const armstrongBetween = (lower, upper) => {
const res = [];
for(let i = lower; i <= upper; i++){
if(isArmstrong(i)){
res.push(i);
};
};
return res;
};
console.log(armstrongBetween(1, 400));Output
The output in the console: −
[ 1, 2, 3, 4, 5, 6, 7, 8, 9, 153, 370, 371 ]