Adding numbers in two different array in Javascript

Question

I am trying to add two different arrays in following manner.

A = [1 2 3 4] B = [2 3 4 5]

A + B = [3 5 7 9]

<script>
function myFunction1(){

var Mmax1 = new Array();
var Mmax2 = new Array();
var L = document.getElementById("txt1").value;
var w = document.getElementById("txt2").value;
var P = document.getElementById("txt3").value;
var a = document.getElementById("txt4").value;  

    for (var x = 0; x <= L; x += 1) {
        sum[x] = x
        Mmax1[x] = w * x / 2 * (L-x) 
        Mmax2[i] = P*a*(i-a)/i;
    }
        Mmax = Mmax1 + Mmax2

</script>

How can this be done in Javascript? Thank you!

Answer 1

Well we want to make sure the arrays aren't null and that the lengths are the same...then we can just iterate.

var A = [1, 2, 3, 4], B = [2, 3, 4, 5]
var sum = [];
    
function sumArray(a, b) {
  if (a != null && b != null && a.length == b.length) {
    for (var i = 0, len = a.length; i < a.length; i++) {
      sum.push(a[i] + b[i]);
    }
  }

  return sum;
}

console.log(sumArray(A, B));

Answer 2

Use Array#map method.

var A = [1, 2, 3, 4],
  B = [2, 3, 4, 5];

var res = A
  // iterate over first array
  .map(function(v, i) {
    // sum up first array value and second
    // array value fetched by index
    return v + B[i];
  });

console.log(res);

Answer 3

var AB=[];
for(var x in A){
    AB.push(A[x]+B[x]);
}

console.log(AB);