When we have two separate array and we want to make key value pair from that two array, we can use array’s reduce function like below:

var columns = ["Date", "Number", "Size", "Location", "Age"];
var rows = ["2001", "5", "Big", "Sydney", "25"];
var result =  rows.reduce(function(result, field, index) {
  result[columns[index]] = field;
  return result;
}, {})

console.log(result);

Output:

{
  Date: "2001",
  Number: "5",
  Size: "Big",
  Location: "Sydney",
  Age: "25"
}