1function sumArray(a, b) {
2      var c = [];
3      for (var i = 0; i < Math.max(a.length, b.length); i++) {
4        c.push((a[i] || 0) + (b[i] || 0));
5      }
6      return c;
7}

1var twoSum = function(nums, target) {
2  const indicies = {}
3  
4  for (let i = 0; i < nums.length; i++) {
5    const num = nums[i]
6    if (indicies[target - num] != null) {
7      return [indicies[target - num], i]
8    }
9    indicies[num] = i
10  }
11};

1function sumArrays(...arrays) {
2  const n = arrays.reduce((max, xs) => Math.max(max, xs.length), 0);
3  const result = Array.from({ length: n });
4  return result.map((_, i) => arrays.map(xs => xs[i] || 0).reduce((sum, x) => sum + x, 0));
5}
6
7console.log(...sumArrays([0, 1, 2], [1, 2, 3, 4], [1, 2])); // 2 5 5 4

1var twoSum = function(nums, target) {
2    //hash table
3    var hash = {};
4
5    for(let i=0; i<=nums.length; i++){
6      //current number
7        var currentNumber = nums[i];
8        //difference in the target and current number
9        var requiredNumber = target - currentNumber;
10        // find the difference number from hashTable
11        const index2 = hash[requiredNumber];
12
13        // if number found, return index 
14        // it will return undefined if not found
15        if(index2 != undefined) {
16            return [index2, i]
17        } else {
18           // if not number found, we add the number into the hashTable
19            hash[currentNumber] = i;
20
21        }
22    }
23};