[Beginner1]

Hello,
I am working on small project that requires this:

have three fields:

1. Basic price:
2. NET price
3. Gross price

NET Price is determend by Profit margin rate
Gross price is detremend by VAT rate

I need to be able to "live" update all three fields no mater where is the input.

e.g if I type in basic price Net price and gross price will update automaticly, or if typed Gross price Net price and basic price will update automaticly

So far I have his:
1. NET and gross price update:

function updateNet() {
	if( document.adminForm.product_price_incl_tax.value != '' ) {
		var taxRate = getTaxRate();

		var r = new RegExp("\,", "i");
		document.adminForm.product_price_incl_tax.value = document.adminForm.product_price_incl_tax.value.replace( r, "." );

		var netValue = document.adminForm.product_price_incl_tax.value;

		if (taxRate > 0) {
			netValue = netValue / (taxRate + 1);
		}

		document.adminForm.product_price.value = doRound(netValue, 5);
	}
}

2. gross and NET price update:

function updateGross() {
	if( document.adminForm.product_price.value != '' ) {
		var taxRate = getTaxRate();

		var r = new RegExp("\,", "i");
		document.adminForm.product_price.value = document.adminForm.product_price.value.replace( r, "." );

		var grossValue = document.adminForm.product_price.value;

		if (taxRate > 0) {
			grossValue = grossValue * (taxRate + 1);
		}

		document.adminForm.product_price_incl_tax.value = doRound(grossValue, 5);
	}
}

3. Basic and NET price update:

function updateProfit() {
	if( document.adminForm.product_profitmargin_price.value != '' ) {
		var profitRate = getProfitRate();

		var r = new RegExp("\,", "i");
		document.adminForm.product_profitmargin_price.value = document.adminForm.product_profitmargin_price.value.replace( r, "." );
		document.adminForm.product_price_incl_tax.value = document.adminForm.product_price_incl_tax.value.replace( r, "." );

		var netValue = document.adminForm.product_profitmargin_price.value;

		if (profitRate > 0) {
			netValue = netValue * (profitRate + 1);
		}
		document.adminForm.product_price.value = doRound(netValue, 5);
	}
}

so I am missing as described above, possibility to update all three fields at once and currently stacked with this partial solution

Any help is highly appreciated.