Convert number to comma separated format

[Sruthi P]

How to convert a number to comma separated format? 

Add this in connection script

function numberWithCommas(x) {
     return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}

var cost = changedItem.attributes.data[0].cost_amount;
var cost_comma=numberWithCommas(cost);