Q:

Arrow function expected a return value

How can I fix this warning?  Is it wrong the way I'm using .map? 
I'm trying to display total sales and total revenue in each month that is being received through another array that contains that info, to later on display it on a chart. 
var arrEneSales = [0, 0, 0, 0, 0, 0];
var arrJulSales = [0, 0, 0, 0, 0, 0];

var arrMoneyEne = [0, 0, 0, 0, 0, 0];
var arrMoneyJul = [0, 0, 0, 0, 0, 0];

this.state.sales.map((item) => {
  var date = new Date(item[0].q1_date.seconds * 1000);
  if (date.getMonth() + 1 < 6) {
    arrEneSales[date.getMonth() + 1] += 1;
    arrMoneyEne[date.getMonth() + 1] += item[0].total;
  } else {
    arrJulSales[date.getMonth() + 1] += 1;
    arrMoneyJul[date.getMonth() + 1] += item[0].total;
  }
});

A:

Map used for returning array.  If you don't want to return anything just iterate through array then don't use map use forEach like this. 
this.state.sales.forEach((item) => {
  var date = new Date(item[0].q1_date.seconds * 1000);
  if (date.getMonth() + 1 < 6) {
    arrEneSales[date.getMonth() + 1] += 1;
    arrMoneyEne[date.getMonth() + 1] += item[0].total;
  } else {
    arrJulSales[date.getMonth() + 1] += 1;
    arrMoneyJul[date.getMonth() + 1] += item[0].total;
  }
});

Map work like this. 
var returnedArray = this.state.sales.map((item) => {
  var date = new Date(item[0].q1_date.seconds * 1000);
  if (date.getMonth() + 1 < 6) {
    arrEneSales[date.getMonth() + 1] += 1;
    arrMoneyEne[date.getMonth() + 1] += item[0].total;
  } else {
    arrJulSales[date.getMonth() + 1] += 1;
    arrMoneyJul[date.getMonth() + 1] += item[0].total;
  }
  return item;
});

