Process ledger to return final balance by name or balance on specified date for name

ledger.js

var ledgerDateMap = {};

/*
Parses ledger data into JSON obj and sorts by date 
*/

function parseLedger(ledgerData) {
  var preArr=ledgerData.split(' '), ledgerArr = [];
  
  function sortByDate(a,b) {
    return a.date-b.date;
  }
  
  for (var i in preArr) {
    var entry = preArr[i].split(',');
    ledgerArr.push({
      date: Date.parse(entry[0]),
      payor: entry[1],
      payee: entry[2],
      amount: parseFloat(entry[3])
    });
  } 
   
  return ledgerArr.sort(sortByDate);  
}

/* 
Generates balance data obj for requested name by date.  
*/

function calcBalanceForName(data,name) {
  var balanceData = [],
  balance = 0;
    
  function balancePush(date,balance) {
    var lookupDateIndex = ledgerDateMap[date];

    if (lookupDateIndex >= 0)
      balanceData[lookupDateIndex].balance = balance;

    balanceData.push({
      date: date,
      balance: balance 
    });
    
    ledgerDateMap[date] = balanceData.length-1;
  }
  
  for (var i in data) { 
    var date = data[i].date;
    
    if (data[i].payor == name) {
      balance -= data[i].amount;
      balancePush(date,balance);
    }
    else if (data[i].payee == name) {
     balance += data[i].amount;
     balancePush(date,balance);
    }
  }
  
  return balanceData;  
}

/* 
Finds latest balance for date provided 
*/

function findByDate(data, lookUpDate) {
  var date = Date.parse(lookUpDate);
  var lookupDateIndex = ledgerDateMap[date];
  
  function findClosestDate(data,date){
    var dates = [];
    for (var i in data) {
      if (data[i].date < date)
        dates.push(data[i].date);
    }
  
    return dates[dates.length-1];
  }
  
  if (lookupDateIndex >= 0)
    return data[lookupDateIndex].balance;

  var closesDate = findClosestDate(data,date);
  lookupDateIndex = ledgerDateMap[closesDate];
  
  if (lookupDateIndex >= 0)
    return data[lookupDateIndex].balance;

  return 0;
}

/* 
Function to run via console to return final balance by name
*/

function finalBalanceByName(ledgerData,name) {
  var ledgerArr = parseLedger(ledgerData);
  var balanceData = calcBalanceForName(ledgerArr,name);
  
  return balanceData[balanceData.length-1].balance;
}

/* 
Function to run via console to return final balance by name and specified date
*/

function balanceByNameDate(ledgerData,name,date) {
  var ledgerArr = parseLedger(ledgerData);
  var balanceData = calcBalanceForName(ledgerArr,name);
  var balanceByDate = findByDate(balanceData,date);
  
  return balanceByDate;
  
}

//console.log(finalBalanceByName("2015-01-17,john,mary,125.25 2015-01-17,john,supermarket,20.00 2015-01-17,mary,insurance,100.25","supermarket"));

console.log(balanceByNameDate("2015-01-16,john,mary,125.25 2015-01-17,john,supermarket,20.00 2015-01-19,mary,supermarket,-50.00 2015-01-17,mary,insurance,100.25","supermarket","2015-01-17"));