Javascript Ajax jQuery Html PHP Example Quiz New MORE

How to Auto Calculate GST in Javascript by select price

<!DOCTYPE html>
<form name="frm-pin" method="post" action="pin-index-a.php">
<input type="hidden" name="mode" value="PinRequest" /> 
<label class="w3-text-green"><b>Choose price</b></label>
<select name="tot_pin_requested" onchange="calculateAmount(this.value)" required>
		<option value="" disabled selected>Choose your option</option>
		<option value="1000">1000</option>
		<option value="2000">2000</option>
		<option value="3000">3000</option>
		<option value="4000">4000</option>
		<option value="5000">5000</option>
<label><b>Total Amount after tax</b></label>
<input class="w3-input w3-border" name="tot_amount" id="tot_amount" type="text" readonly>
function calculateAmount(val)
	var price = val * 1;
	/*display the result*/
	var tot_price=price+(price*0.18);
	var divobj = document.getElementById('tot_amount');
	divobj.value = tot_price;

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