res.js

/**
 * Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.
 * 
 * The update(i, val) function modifies nums by updating the element at index i to val.
 * 
 * Example:
 * Given nums = [1, 3, 5]
 * sumRange(0, 2) -> 9
 * update(1, 2)
 * sumRange(0, 2) -> 8
 * 
 * Note:
 * The array is only modifiable by the update function.
 * 
 * You may assume the number of calls to update and sumRange function is distributed evenly.
 * 
 * res.js
 * @authors Joe Jiang (hijiangtao@gmail.com)
 * @date    2017-02-28 20:10:00
 * @version $Id$
 */

/**
 * @param {number[]} nums
 */
var NumArray = function(nums) {
    this.nums = nums;
};

/** 
 * @param {number} i 
 * @param {number} val
 * @return {void}
 */
NumArray.prototype.update = function(i, val) {
    this.nums[i] = val;
};

/** 
 * @param {number} i 
 * @param {number} j
 * @return {number}
 */
NumArray.prototype.sumRange = function(i, j) {
    let sum = 0;
    for (let ind=i; ind<=j; ind++) {
        sum += this.nums[ind];
    }
    
    return sum;
};

/** 
 * Your NumArray object will be instantiated and called as such:
 * var obj = Object.create(NumArray).createNew(nums)
 * obj.update(i,val)
 * var param_2 = obj.sumRange(i,j)
 */