sum(range(10),-1) ? code example

Example: Sum All Numbers in a Range

const sumAll = arr => {
   let maxNumber = Math.max(...arr)
   let minNumber = Math.min(...arr)
   let numbersArray = []

   for(let i = minNumber; i <= maxNumber; i++){
     numbersArray.push(i)
   }
   return numbersArray.reduce((acc, cur) => acc + cur, 0)
}

sumAll([1, 4]);