Array_Partition_I.js

/**
 * @param {number[]} nums
 * @return {number}
 */
var arrayPairSum = function(nums) {
    var number = 0;
    nums.sort(function(a, b) { return a-b; });
    for (var i = 0; i < nums.length; i += 2)
    	number += nums[i];
    return number;
};