I did but using .js file with below code but I need it using a custom script
calculate_f_total: function() {
var me = this;
this.frm.doc.foreign_total = 0.0;$.each(this.frm.doc["items"] || [], function(i, item) { if (item.currency =='USD') { me.frm.doc.foreign_total += item.amount; } else if(item.is_alt_item =='ALT') { me.frm.doc.foreign_total += item.amount * 0; } });
},