Mask an array to calculate sub-array average

mask-array.js

function ave(arr) {
    if (arr && arr.length) {
        //easy way to get array total is using reduce; c is current   
        const total = arr.reduce((a, c) => {
            return a + c;
        });
        return total / arr.length;
    }
    throw new Error('wrong arr');
};


function calculate(array, win_size) {
    const result = [];
    const totalLength = array.length;
    //always do error checking
    if (!win_size || win_size > totalLength) {
        throw new Error('wrong size');
    }
   //cursor at 0; and move downwards to the end; 
   for (let i = 0; i < totalLength; i++) {
        if ((i) + win_size <= totalLength) {
            let tempArray = [];
            for (let j = 0; j < win_size; j++) {
                console.log(i)
                tempArray.push(array[i + j]);
            }
            //get part of the array and a new one;
            result.push(ave(tempArray));
        }else{
          //if cover moves out of the range, stop here!             
       }
     }
    return result;
}

console.log(calculate([2,2,2,1,1,1,1,4,2,3], 3)