SOURCE

const data = [['a1', 'b1', 'c1', 'd1'], ['a1', 'b1', 'c2', 'd2'], ['a1', 'b1', 'c2', 'd3'], ['a1', 'b2', 'c3', 'd4'], ['a2', 'b3', 'c4', 'd5'], ['a2', 'b3', 'c4', 'd6'], ['a2', 'b4', 'c5', 'd7'], ['a2', 'b4', 'c6', 'd8'], ];

function createObject(arr) {
  return arr.reduce((result, currentValue, index, arr) => {
    return result
  },
  {
    a: 1
  })
};

console.log(JSON.stringify(createObject(data)))