Need to update the Date format on my Google Mail Script - date

Question

I'm creating a Gmail script that includes 5 variables, one of which is a due date. I just want it to populate as MM/DD/YYYY, however, it is currently populating as Thu Sep 13 2018 00:00:00 GMT-0400 (EDT).
Is there a way I can do that? I've pasted my code below for your reference. Any assistance is much appreciated.
function getRowsData(sheet, range, columnHeadersRowIndex) {
columnHeadersRowIndex = columnHeadersRowIndex || range.getRowIndex() - 1;
var numColumns = range.getEndColumn() - range.getColumn() + 1;
var headersRange = sheet.getRange(columnHeadersRowIndex, range.getColumn(), 1, numColumns);
var headers = headersRange.getValues()[0];
return getObjects(range.getValues(), normalizeHeaders(headers));
}
function getObjects(data, keys) {
var objects = [];
for (var i = 0; i < data.length; ++i) {
var object = {};
var hasData = false;
for (var j = 0; j < data[i].length; ++j) {
var cellData = data[i][j];
if (isCellEmpty(cellData)) {
continue;
}
object[keys[j]] = cellData;
hasData = true;
}
if (hasData) {
objects.push(object);
}
}
return objects;
}
function normalizeHeaders(headers) {
var keys = [];
for (var i = 0; i < headers.length; ++i) {
var key = normalizeHeader(headers[i]);
if (key.length > 0) {
keys.push(key);
}
}
return keys;
}
function normalizeHeader(header) {
var key = "";
var upperCase = false;
for (var i = 0; i < header.length; ++i) {
var letter = header[i];
if (letter == " " && key.length > 0) {
upperCase = true;
continue;
}
if (!isAlnum(letter)) {
continue;
}
if (key.length == 0 && isDigit(letter)) {
continue;
}
if (upperCase) {
upperCase = false;
key += letter.toUpperCase();
} else {
key += letter.toLowerCase();
}
}
return key;
}
function isCellEmpty(cellData) {
return typeof(cellData) == "string" && cellData == "";
}
function isAlnum(char) {
return char >= 'A' && char <= 'Z' ||
char >= 'a' && char <= 'z' ||
isDigit(char);
}
function isDigit(char) {
return char >= '0' && char <= '9';