how to compute array value and add extra file with sum of amount javascript

https://jsfiddle.net/dy6vhnsc/

expected like this

myData: [{
      id: 1,
      name: 'Russell',
      country: 'Windes',
      amount: 7,
      myaddedResult: [
        {
            id: 3,
            name: 'Watson',
            country: 'Australia',
            amount: 9,
            sumOfAmount: 16
          },
          {
            id: 4,
            name: 'Marcus',
            country: 'England',
            amount: 10,
            sumOfAmount: 17
          }
      ]
    },
    {
      id: 2,
      name: 'Smith',
      country: 'USA',
      amount: 8
    }
  ],
  ownerData: [{
      id: 3,
      name: 'Watson',
      country: 'Australia',
      amount: 9
    },
    {
      id: 4,
      name: 'Marcus',
      country: 'England',
      amount: 10
    }
  ]

how to add new field and add sum of amount into the new array in javascript what would be best option please guide

Thanks