Adding commas to numbers in expression counter

[chloeg2706]

Hi

I know this question has been answered a few times already but I'm struggling to figure out what part of the expressiojn I need to add and where it needs to be added in order for me to get comma's. I've attached an image of what I have of the expression so far, can anyone help me?

[Mylenium]

Something like this perhaps:

mVal=thisComp.layer("XYZ").effect("Slider")("Slider");

mString=Math.round(mVal).toString();

mPre=mString.substring(1,2);

mPost=mString.substring(mString.length,-3);

mPre()+","+mPost

Mylenium

[Rick Gerard]

Dan Ebberts's Universal Counter

Enough said...