Acrobat v9 JavaScript Alert Box - any way to add space or line break after each array item?

Question

I have a Document level Javascript used to identify blank required fields and is triggered on document actions, Print and Save. The script identifies the blank required fields, counts them, and outputs to an Alert box indicating the number of required fields blank and lists the fields by tooltip name. The script identifies the required fields by an asterisk at the end of each tool tip.
My question is there any way to add a space or a line break after the comma for each listed item?
Here is an image of the output where the listed items are all run together.
Here is the code:
function validateFields()
//a counter for the number of empty fields
var flg = 0
// count all the form fields
var n = this.numFields
//create an array to contain the names of required fields
//if they are determined to be empty
var fArr = new Array();
//loop through all fields and check for those that are required
// all fields that have a '*' in their tool tip are required
for(var i = 0;i<n;i++){
var fn = this.getNthFieldName(i);
var f = this.getField(fn);
//tool tip is the fields\'s 'userName' property;
var tt = f.userName
//test for the '*';
if(tt.indexOf('*')!=-1 && f.value == f.defaultValue){
//increment the counter of empty fields;
flg++;
//add the fields userName (tool tip) to the list of empty field names;
fArr[fArr.length] = tt;
//now display a message if there are empty fields
if(flg>0){
app.alert('There are '+flg+' fields that require a value\n\n'+ fArr,3)
else{
this.print();

Answer 1

Thank you! The alert box array items now have a line break, image below.  You know you have made my day and possibly several weeks as now I have more understanding about how to apply everything I have been reading in the Acrobat JavaScript guide and of course as soon as you pointed out using a "join", that triggered some old-days of working with Access and SQL queries.
I will work on the required attribute to see how I might reference it.  I am laughing at myself now - good luck to me in figuring it out as I was very stick-in-the-mud regarding the line break issue.
Thanks again and here is the result of the updated code: