refactor: split data update responsibilty to multiple functions

Apply "single responsibilty principle"
diff --git a/erpnext/public/js/utils/barcode_scanner.js b/erpnext/public/js/utils/barcode_scanner.js
index 455b971..4d73ab9 100644
--- a/erpnext/public/js/utils/barcode_scanner.js
+++ b/erpnext/public/js/utils/barcode_scanner.js
@@ -9,6 +9,13 @@
 		this.items_table_name = opts.items_table_name || "items";
 		this.items_table = this.frm.doc[this.items_table_name];
 
+		// any API that takes `search_value` as input and returns dictionary as follows
+		// {
+		//     item_code: "HORSESHOE", // present if any item was found
+		//     bar_code: "123456", // present if barcode was scanned
+		//     batch_no: "LOT12", // present if batch was scanned
+		//     serial_no: "987XYZ", // present if serial no was scanned
+		// }
 		this.scan_api = opts.scan_api || "erpnext.selling.page.point_of_sale.point_of_sale.search_for_serial_or_batch_or_barcode_number";
 	}
 
@@ -35,64 +42,74 @@
 				return;
 			}
 
-			me.modify_table_after_scan(data);
+			me.update_table(data.item_code, data.barcode, data.batch_no, data.serial_no);
 		});
-		this.clean_up();
 	}
 
-
-	modify_table_after_scan(data) {
+	update_table(item_code, barcode, batch_no, serial_no) {
 		let cur_grid = this.frm.fields_dict[this.items_table_name].grid;
-		let row_to_modify = null;
+		let row = null;
 
 		// Check if batch is scanned and table has batch no field
-		let batch_no_scan = Boolean(data.batch_no) && frappe.meta.has_field(cur_grid.doctype, "batch_no");
+		let batch_no_scan = Boolean(batch_no) && frappe.meta.has_field(cur_grid.doctype, "batch_no");
 
 		if (batch_no_scan) {
-			row_to_modify = this.get_batch_row_to_modify(data.batch_no);
+			row = this.get_batch_row_to_modify(batch_no);
 		} else {
 			// serial or barcode scan
-			row_to_modify = this.get_row_to_modify_on_scan(row_to_modify, data);
+			row = this.get_row_to_modify_on_scan(row, item_code);
 		}
 
-		if (!row_to_modify) {
+		if (!row) {
 			// add new row if new item/batch is scanned
-			row_to_modify = frappe.model.add_child(this.frm.doc, cur_grid.doctype, this.items_table_name);
+			row = frappe.model.add_child(this.frm.doc, cur_grid.doctype, this.items_table_name);
 			// trigger any row add triggers defined on child table.
-			this.frm.script_manager.trigger(`${this.items_table_name}_add`, row_to_modify.doctype, row_to_modify.name);
+			this.frm.script_manager.trigger(`${this.items_table_name}_add`, row.doctype, row.name);
 		}
 
-		if (this.is_duplicate_serial_no(row_to_modify, data.serial_no)) {
+		if (this.is_duplicate_serial_no(row, serial_no)) {
 			this.clean_up();
 			return;
 		};
 
-		this.show_scan_message(row_to_modify.idx, row_to_modify.item_code);
-		this.set_scanned_values(row_to_modify, data);
+		this.show_scan_message(row.idx, row.item_code);
+		this.set_item(row, item_code);
+		this.set_serial_no(row, serial_no);
+		this.set_batch_no(row, batch_no);
+		this.set_barcode(row, barcode);
+		this.clean_up();
 	}
 
-	set_scanned_values(row_to_modify, data) {
+	set_item(row, item_code) {
+		frappe.model.set_value(row.doctype, row.name, {
+			item_code: item_code,
+			qty: (row.qty || 0) + 1, // TODO: harcoded fieldname
+		});
+	}
+
+	set_serial_no(row, serial_no) {
+		if (serial_no && frappe.meta.has_field(row.doctype, "serial_no")) {
+			// TODO: fieldname hardcoded
+			const value = row["serial_no"] + '\n' + serial_no;
+			frappe.model.set_value(row.doctype, row.name, "serial_no", value);
+		}
+	}
+
+	set_batch_no(row, batch_no) {
+		if (batch_no && frappe.meta.has_field(row.doctype, "batch_no")) {
+			// TODO: fieldname hardcoded
+			frappe.model.set_value(row.doctype, row.name, "batch_no", batch_no);
+		}
+	}
+
+	set_barcode(row, barcode) {
 		// increase qty and set scanned value and item in row
+		// XXX: tightly coupled global flag on frm object used in transaction.js -_-
 		this.frm.from_barcode = this.frm.from_barcode ? this.frm.from_barcode + 1 : 1;
-		frappe.model.set_value(row_to_modify.doctype, row_to_modify.name, {
-			item_code: data.item_code,
-			qty: (row_to_modify.qty || 0) + 1
-		});
-
-		['serial_no', 'batch_no', 'barcode'].forEach(field => {
-			if (data[field] && frappe.meta.has_field(row_to_modify.doctype, field)) {
-				let is_serial_no = row_to_modify[field] && field === "serial_no";
-				let value = data[field];
-
-				if (is_serial_no) {
-					value = row_to_modify[field] + '\n' + data[field];
-				}
-
-				frappe.model.set_value(row_to_modify.doctype, row_to_modify.name, field, value);
-			}
-		});
-
-		this.clean_up();
+		if (barcode && frappe.meta.has_field(row.doctype, "barcode")) {
+			// TODO: fieldname hardcoded
+			frappe.model.set_value(row.doctype, row.name, "barcode", barcode);
+		}
 	}
 
 	show_scan_message (idx, exist = null) {
@@ -129,9 +146,9 @@
 		return existing_batch_row || null;
 	}
 
-	get_row_to_modify_on_scan(row_to_modify, data) {
+	get_row_to_modify_on_scan(row_to_modify, item_code) {
 		// get an existing item row to increment or blank row to modify
-		const existing_item_row = this.items_table.find(d => d.item_code === data.item_code);
+		const existing_item_row = this.items_table.find(d => d.item_code === item_code);
 		const blank_item_row = this.items_table.find(d => !d.item_code);
 
 		if (existing_item_row) {