Integrate Paypal button with custom value

Successfully integrate with Paypal button with pass over different amount based on the selection.

paypal.Buttons({
createOrder: function(data, actions) {
// This function sets up the details of the transaction, including the amount and line item details.
mySelectedVal = document.getElementById("abc");
return actions.order.create({
purchase_units: [{
amount: {
value: mySelectedVal.options[mySelectedVal.selectedIndex].value
}
}]
});
},
onApprove: function(data, actions) {
// This function captures the funds from the transaction.
return actions.order.capture().then(function(details) {
// This function shows a transaction success message to your buyer.
alert('Transaction completed by ' + details.payer.name.given_name);
});
}
}).render('#paypal-button-container');
//This function displays Smart Payment Buttons on your web page.