parseCSV.js

function map(arr, func) {
 return arr.map(func);
}

// IF you are super particular about ordering
function parseCSV(csv) {
  var peopleArray = csv.split('\n');
  var peopleArrayWithSplitNameElements = map(peopleArray, function(str){
    return str.split(',');
  })
  var result = map(peopleArrayWithSplitNameElements, function(arr){
    var personObj = {
      name: {},
    };
   if (arr[0]) {
    personObj.name.first = arr[0];
   }
   if (arr[1]) {
     personObj.name.middle = arr[1];
   }
   if (arr[2]) {
    personObj.name.last = arr[2]
   }
   if (arr[3]) {
   personObj.age = arr[3];
   }
    return personObj;
  })
  return result;
}

// How people would actually write it
function parseCSV(csv) {
  var peopleArray = csv.split('\n');
  var peopleArrayWithSplitNameElements = map(peopleArray, function(str){
    return str.split(',');
  })
  var result = map(peopleArrayWithSplitNameElements, function(arr){
    var personObj = {
      name: {
        first: arr[0],
        last: arr[2],
      },
      age: arr[3],
    };
   if (arr[1]) {
     personObj.name.middle = arr[1];
   }
    return personObj;
  })
  return result;
}

// using native functions

// function parseCSV(csv) {
//   return csv.split('\n')
//   .map(function(str) {
//     return str.split(',')
//   })
//  .map(function(arr) {
//    var personObj = {
//       name: {
//         first: arr[0],
//         last: arr[2],
//       },
//       age: arr[3],
//     };
//    if (arr[1]) {
//      personObj.name.middle = arr[1];
//    }
//     return personObj;
//   })
// }

var csv = "Alyssa,P.,Hacker,26\nBen,,Bitdiddle,34\nEva,Lu,Ator,40\nLem,E.,Tweakit,45\nLouis,,Reasoner,21"

console.log(parseCSV(csv));