update

Author: LadyBluenotes

src/routes/reference/jsx-attributes/attr.mdx

@@ -28,13 +28,13 @@ See the[TypeScript](/configuration/typescript#forcing-properties-and-custom-attr
 
 - **Type:** attribute value
 
-Value written to the attribute after the `attr:` prefix is removed.
+Value passed to normal attribute serialization after the `attr:` prefix is removed.
 
 ## Behavior
 
-- `attr:name={value}` writes the value to the `name` attribute.
-- The `attr:` prefix is removed before the attribute is written.
-- This is useful when an element expects data through attributes rather than DOM properties.
+- `attr:name={value}` writes the value to the `name` attribute after the `attr:` prefix is removed.
+- In the DOM runtime, `attr:name={undefined}` or `attr:name={null}` removes the attribute.
+- In SSR output, the stripped attribute name and escaped value are written as HTML.
 
 ## Examples