const sumOfArray = (arr, i=0) => {
    //return arr.reduce((acc, curr) => acc+curr , 0)
    if(i === arr.length ){
        return 0
    }
    return arr[i] + sumOfArray(arr, i + 1) 

    
    
}

console.log(sumOfArray([1,2,3,4,5,6]))