Onchange client script for calculation

[SAM321]

Hi all , so this is my script for calculating values in field on changing value in GST field....

How can i modify this script...  Initially CGST  and SGST values '320'wil l be auto calculated at that time IGST should show only '0'...when i manually change CGST and SGST to '0' only at that time IGST should show '640'...

can i get script for it

[lp6]

that is expected right when you give same value then it will give the sum other wise it will be 0, If you don't want 0 then replace with space in code

[Ravi Gaurav]

var gst = parseFloat(document.getElementById("gst").value);
var cgst = 0;
var sgst = 0;
var igst = 0;

if (gst !== 0) {
cgst = sgst = gst / 2;
}

if (cgst === 0 && sgst === 0) {
igst = 640;
} else {
igst = 0;
}

document.getElementById("cgst").value = cgst.toFixed(2);
document.getElementById("sgst").value = sgst.toFixed(2);
document.getElementById("igst").value = igst.toFixed(2);