Using sliding window pattern to find something in an array which has to be a sub array.

sliding_window_pattern.js

let maxSubarraySum = (arr,n)=>{
    if(n<1 || n>arr.length){return undefined}
    let maxSum = -Infinity;
    let windowSum = arr
					.filter((item,index)=>index<n)
                    .reduce((sum,item)=>sum+item,0);
	//console.log('Baslangic ara toplami:', windowSum);
	for(let x= 0; x<arr.length-n;x++){
		
		windowSum =windowSum-arr[x]+arr[x+n]
		//console.log('ara toplam:', windowSum)
		maxSum = Math.max(maxSum,windowSum)
	}
return maxSum;
}



let arr = [1,2,3,8,4,5,6,7,5,2];
//console.log(maxSubarraySum(arr,3))