Intermediate Algorithm Scripting: Sum All Numbers in a Range

sumAll.js

// We'll pass you an array of two numbers. Return the sum of those two numbers plus the sum of all the numbers between them.
// The lowest number will not always come first.

// This was my solution:
function sumAll(arr) {
  let start=arr[0] > arr[1]?arr[1]:arr[0];
  let end=arr[0] > arr[1]?arr[0]:arr[1];
  let sum=0;
  for (let i=start; i<=end; i++) {
    sum+=i;
  }

  return sum;
}

// But this is an awesome solution !

function sumAll(arr) {
    var sum = 0;
    for (var i = Math.min(...arr); i <= Math.max(...arr); i++){
        sum += i;
    }
  return sum;
}

// Also, I believe this would be a faster solution, specially if the range between numbers is large:
function sumAll(arr) {
  return (Math.abs(arr[0]-arr[1])+1)*(arr[0]+arr[1])/2;
}

sumAll([1, 4]);