Fetching value when field change

Example, get default "cash_bank_account" when mode_of_payment is updated

On client side:

cur_frm.cscript.mode_of_payment = function(doc) {
 cur_frm.call({
  method: "get_bank_cash_account",
  args: { mode_of_payment: doc.mode_of_payment }
 });
}