Implements preload option for scripts

Author: joaopslins

webpack_loader/utils.py

@@ -62,9 +62,14 @@ def get_as_tags(bundle_name, extension=None, config='DEFAULT', attrs='', is_prel
     tags = []
     for chunk in bundle:
         if chunk['name'].endswith(('.js', '.js.gz')):
-            tags.append((
-                '<script src="{0}" {1}></script>'
-            ).format(chunk['url'], attrs))
+            if is_preload:
+                tags.append((
+                    '<link rel="preload" as="script" href="{0}" {1}/>'
+                ).format(chunk['url'], attrs))
+            else:
+                tags.append((
+                    '<script src="{0}" {1}></script>'
+                ).format(chunk['url'], attrs))
         elif chunk['name'].endswith(('.css', '.css.gz')):
             tags.append((
                 '<link href="{0}" rel={2} {1}/>'