diff --git a/.gitignore b/.gitignore
index b6e47617de1..65a3e9c663f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -127,3 +127,10 @@ dmypy.json
 
 # Pyre type checker
 .pyre/
+
+.eslintignore
+.eslintrc.json
+jsconfig.json
+package.json
+package-lock.json
+node_modules/
diff --git a/sale_discount/__init__.py b/sale_discount/__init__.py
new file mode 100644
index 00000000000..0650744f6bc
--- /dev/null
+++ b/sale_discount/__init__.py
@@ -0,0 +1 @@
+from . import models
diff --git a/sale_discount/__manifest__.py b/sale_discount/__manifest__.py
new file mode 100644
index 00000000000..7bf22334fab
--- /dev/null
+++ b/sale_discount/__manifest__.py
@@ -0,0 +1,9 @@
+{
+    'name': 'sale_discount',
+    'depends': ['base', 'sale'],
+    'application': True,
+    'installable': True,
+    'author': 'estate',
+    'category': 'Tutorials',
+    'license': 'AGPL-3',
+}
diff --git a/sale_discount/models/__init__.py b/sale_discount/models/__init__.py
new file mode 100644
index 00000000000..2d7ee6c3dc7
--- /dev/null
+++ b/sale_discount/models/__init__.py
@@ -0,0 +1,2 @@
+from . import sale_order
+from . import sale_order_line
diff --git a/sale_discount/models/sale_order.py b/sale_discount/models/sale_order.py
new file mode 100644
index 00000000000..dc9976d709f
--- /dev/null
+++ b/sale_discount/models/sale_order.py
@@ -0,0 +1,35 @@
+import re
+from odoo import models, api
+
+
+class SaleOrder(models.Model):
+    _inherit = 'sale.order'
+
+    @api.onchange('order_line')
+    def _onchange_recalculate_global_discount(self):
+        discount_lines = self.env['sale.order.line']
+        for line in self.order_line:
+            if line._is_global_discount():
+                discount_lines += line
+
+        if not discount_lines:
+            return
+
+        product_lines = self.env['sale.order.line']
+        for line in self.order_line:
+            if not line._is_global_discount() and not line.is_downpayment:
+                product_lines += line
+
+        if not product_lines:
+            self.order_line -= discount_lines
+            return
+
+        subtotal = 0
+        for line in product_lines:
+            subtotal += line.price_subtotal
+
+        for discount_line in discount_lines:
+            match = re.search(r"(\d+(?:\.\d+)?)%", discount_line.name)
+            if match:
+                percent = float(match.group(1))
+                discount_line.price_unit = -(subtotal * percent / 100)
diff --git a/sale_discount/models/sale_order_line.py b/sale_discount/models/sale_order_line.py
new file mode 100644
index 00000000000..18cff2bedc6
--- /dev/null
+++ b/sale_discount/models/sale_order_line.py
@@ -0,0 +1,10 @@
+from odoo import models, api
+
+
+class SaleOrderLine(models.Model):
+    _inherit = 'sale.order.line'
+
+    @api.onchange('price_unit', 'product_uom_qty', 'discount')
+    def _onchange_recalc_discount(self):
+        if self.order_id:
+            self.order_id._onchange_recalculate_global_discount()