/**
 * Convert number to Comma separated decimal value
 * @param {int} x
 * @param {string} local default value "en-IN"
 * @returns string
 */
function numberWithCommasAndDecimalPoint(x, local) {
	local = local.length > 0 ? local : "en-IN";
	x = parseFloat(x).toFixed(2);
	var parts = x.toString().split(".");
	parts[0] = parseInt(parts[0]).toLocaleString("en-IN");
	return parts.join(".");
}

Let’s take a look line by line at what the above code does

local = local.length > 0 ? local : “en-IN”;

Checking the local parameter is empty or not. If it is empty, then set value “en-IN” otherwise set the provided local value.

x = parseFloat(x).toFixed(2);

Converting the provided number into float with parseFloat() function

to add decimal point to 2 digits by toFixed(2).

If you want to show 3 digits after decimal point you can pass 3 as argument like below

x.toFixed(3)

input: 1234.445500 output: 1234.445

var parts = x.toString().split(“.”);

toString() converts the number to string and split() function is splitting the value and make a array.

parts[0] = parseInt(parts[0]).toLocaleString(“en-IN”);

parseInt() converts the string to number. We are converting it to number again because we want to make a comma separated number by using JavaScript method or function toLocaleString() and passing “en-IN” because we want to present the number as Bangladeshi style (India and Bangladesh present the numbers same way). You can also any supported parameters from here.

return parts.join(“.”);

And at last joining the both parts (comma separated value and decimal value) through the join() function.

You can check an example here