[CS3][JS] How to turn negative number in array into string

Question

Hello,
I have a script that compares the array of the geometric bounds of all text frames to the margins for a document (all pages having the same margins). Any frames that do not match the margins are flagged.
In order to compare the array of text frame geometric bounds to two arrays of margins (because they are facing pages), I have to convert the numbers to strings.
My problem is that in the following snippet of code that creates the two margin arrays, the negative of the variables become numbers again. This would not be too difficult to solve except that all the numbers have to be 4 decimal points before converted to strings.
Thanks,
Tom
var myDoc = app.activeDocument;
var marginY1 = myDoc.pages.item(0).marginPreferences.top.toFixed(4);
var marginX1 = myDoc.pages.item(0).marginPreferences.left.toFixed(4);
var marginY2 = (myDoc.documentPreferences.pageHeight - myDoc.pages.item(0).marginPreferences.bottom).toFixed(4);
var marginX2 = (myDoc.documentPreferences.pageWidth - myDoc.pages.item(0).marginPreferences.right).toFixed(4);
var marginsRHand = [marginY1, marginX1, marginY2, marginX2];
var marginsLHand = [marginY1, -marginX2, marginY2, -marginX1];

Answer 1

Well, I think I have solved it. But I don't know why this solves it.
I would think that in the above script all the variables would be numbers and not strings. But the data browser says they are strings.
The solution is:
var marginsLHand = [marginY1, Number(-marginX2).toFixed(4), marginY2, Number(-marginX1).toFixed(4)]
If someone can explain why now all variables in the arrays are strings and not numbers, I'll be happy.
Tom