Maximum Average Subarray I

LeetCode題目: 643. Maximum Average Subarray I

My solution:

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {number}
 */
let findMaxAverage = (nums, k) => {
    let baseValue = nums.slice(0,k).reduce((prev,curr)=>prev+curr,0);
    let tempValue = baseValue;
    for(let i=0; i<nums.length-k; i++) {
        baseValue = baseValue - nums[i] + nums[i+k];
        tempValue = Math.max(baseValue, tempValue);
    }
    return tempValue/k;
};