diff --git a/erpnext/selling/doctype/sales_order/sales_order.js b/erpnext/selling/doctype/sales_order/sales_order.js
index 3b8f4e2..286a013 100644
--- a/erpnext/selling/doctype/sales_order/sales_order.js
+++ b/erpnext/selling/doctype/sales_order/sales_order.js
@@ -124,8 +124,7 @@
 
 				   if(flt(doc.per_delivered, 6) < 100 || flt(doc.per_billed) < 100) {
 					   // close
-					   this.frm.add_custom_button(__('Close'),
-						   function() { me.close_sales_order() }, __("Status"))
+					   this.frm.add_custom_button(__('Close'), () => this.close_sales_order(), __("Status"))
 				   }
 				}
 			   	else if(doc.status === 'Closed') {
@@ -160,57 +159,44 @@
 					if (this.frm.has_perm("submit")) {
 						if(flt(doc.per_delivered, 6) < 100 || flt(doc.per_billed) < 100) {
 							// hold
-							this.frm.add_custom_button(__('Hold'),
-								function() {
-									me.hold_sales_order();
-								}, __("Status"))
+							this.frm.add_custom_button(__('Hold'), () => this.hold_sales_order(), __("Status"))
 							// close
-							this.frm.add_custom_button(__('Close'),
-								function() { me.close_sales_order() }, __("Status"))
+							this.frm.add_custom_button(__('Close'), () => this.close_sales_order(), __("Status"))
 						}
 					}
 
 					// delivery note
 					if(flt(doc.per_delivered, 6) < 100 && ["Sales", "Shopping Cart"].indexOf(doc.order_type)!==-1 && allow_delivery) {
-						this.frm.add_custom_button(__('Delivery'),
-							function() { me.make_delivery_note_based_on_delivery_date(); }, __('Create'));
-						this.frm.add_custom_button(__('Work Order'),
-							function() { me.make_work_order() }, __('Create'));
+						this.frm.add_custom_button(__('Delivery'), () => this.make_delivery_note_based_on_delivery_date(), __('Create'));
+						this.frm.add_custom_button(__('Work Order'), () => this.make_work_order(), __('Create'));
 					}
 
 					// sales invoice
 					if(flt(doc.per_billed, 6) < 100) {
-						this.frm.add_custom_button(__('Invoice'),
-							function() { me.make_sales_invoice() }, __('Create'));
+						this.frm.add_custom_button(__('Invoice'), () => me.make_sales_invoice(), __('Create'));
 					}
 
 					// material request
 					if(!doc.order_type || ["Sales", "Shopping Cart"].indexOf(doc.order_type)!==-1
 						&& flt(doc.per_delivered, 6) < 100) {
-						this.frm.add_custom_button(__('Material Request'),
-							function() { me.make_material_request() }, __('Create'));
-						this.frm.add_custom_button(__('Request for Raw Materials'),
-							function() { me.make_raw_material_request() }, __('Create'));
+						this.frm.add_custom_button(__('Material Request'), () => this.make_material_request(), __('Create'));
+						this.frm.add_custom_button(__('Request for Raw Materials'), () => this.make_raw_material_request(), __('Create'));
 					}
 
 					// make purchase order
 					if(flt(doc.per_delivered, 6) < 100 && allow_purchase) {
-						this.frm.add_custom_button(__('Purchase Order'),
-							function() { me.make_purchase_order() }, __('Create'));
+						this.frm.add_custom_button(__('Purchase Order'), () => this.make_purchase_order(), __('Create'));
 					}
 					// maintenance
 					if(flt(doc.per_delivered, 2) < 100 &&
 							["Sales", "Shopping Cart"].indexOf(doc.order_type)===-1) {
-						this.frm.add_custom_button(__('Maintenance Visit'),
-							function() { me.make_maintenance_visit() }, __('Create'));
-						this.frm.add_custom_button(__('Maintenance Schedule'),
-							function() { me.make_maintenance_schedule() }, __('Create'));
+						this.frm.add_custom_button(__('Maintenance Visit'), () => this.make_maintenance_visit(), __('Create'));
+						this.frm.add_custom_button(__('Maintenance Schedule'), () => this.make_maintenance_schedule(), __('Create'));
 					}
 
 					// project
 					if(flt(doc.per_delivered, 2) < 100 && ["Sales", "Shopping Cart"].indexOf(doc.order_type)!==-1 && allow_delivery) {
-							this.frm.add_custom_button(__('Project'),
-								function() { me.make_project() }, __('Create'));
+							this.frm.add_custom_button(__('Project'), () => this.make_project(), __('Create'));
 					}
 
 					if(!doc.auto_repeat) {
@@ -221,10 +207,8 @@
 				}
 				// payment request
 				if(flt(doc.per_billed)==0) {
-					this.frm.add_custom_button(__('Payment Request'),
-						function() { me.make_payment_request() }, __('Create'));
-					this.frm.add_custom_button(__('Payment'),
-						function() { me.make_payment_entry() }, __('Create'));
+					this.frm.add_custom_button(__('Payment Request'), () => this.make_payment_request(), __('Create'));
+					this.frm.add_custom_button(__('Payment'), () => this.make_payment_entry(), __('Create'));
 				}
 				this.frm.page.set_inner_btn_group_as_primary(__('Create'));
 			}