Please assist to remove last comma from while loop - loops

Question

You're probably assuming this is a duplicate content. It is NOT. I tried all the solutions. Here's the problem.
If you use any solution (substr, rtrim, etc.) inside the while loop, it removes them from each looped item. If you use any solution outside of the while loop, then only the last item of your while loop will show.
Solution inside while loop:
(a,b,c,d,e,) becomes (abcde)
Solution outside while loop:
(a,b,c,d,e,) becomes (e).
Much clarification on this is much appreciated. Thank You for the help! Yes, I've been working on this six hours now. Please help me solve this issue.
Here's my code (without the solution in it):
<script type="text/javascript">
states=new array (<?php $query18 = "SELECT * FROM states ORDER BY state ASC";
$result18 = $db->query($query18);
while ($row18 = $result18->fetch(PDO::FETCH_ASSOC)) {
$states4 = $row18['state'];
$states5 = "\"$states4\",";
echo $states5;
} ?> ); </script>
I am trying to get my list of states (from database) into an array in javascript.

Answer 1

It seems you have not closed closing bracket of array.
Which should be,
states=new array (<?php $query18 = "SELECT * FROM states ORDER BY state ASC"; $result18 = $db->query($query18); ?>);

Answer 2

I don't know much of JavaScript, but you could change your logic as below:
first=1;
while(there-is-data) {
$states4 = ...
if (first) {
first = 0;
$states5 = $states4;
} else {
$states5 = ","\$states4;
}
} // while
You concatenate a comma and the new data for all iterations except the first. For the first, you exclude the comma.