reactive-python · JamesHutchison · Mar 17, 2026 · Mar 17, 2026 · Mar 19, 2026 · Mar 19, 2026
diff --git a/src/reactpy/executors/asgi/pyscript.py b/src/reactpy/executors/asgi/pyscript.py
@@ -17,8 +17,8 @@
     pyscript_component_html,
     pyscript_setup_html,
 )
-from reactpy.executors.utils import vdom_head_to_html
-from reactpy.types import ReactPyConfig, VdomDict
+from reactpy.executors.utils import html_noscript_to_html, vdom_head_to_html
+from reactpy.types import Component, ReactPyConfig, RootComponentConstructor, VdomDict
 
 
 class ReactPyCsr(ReactPy):
@@ -32,6 +32,11 @@ def __init__(
         initial: str | VdomDict = "",
         http_headers: dict[str, str] | None = None,
         html_head: VdomDict | None = None,
+        html_noscript: str
+        | Path
+        | Component
+        | RootComponentConstructor
+        | None = "Enable JavaScript to view this site.",
         html_lang: str = "en",
         **settings: Unpack[ReactPyConfig],
     ) -> None:
@@ -59,6 +64,9 @@ def __init__(
                 commonly used to render a loading animation.
             http_headers: Additional headers to include in the HTTP response for the base HTML document.
             html_head: Additional head elements to include in the HTML response.
+            html_noscript: String, Path to an HTML file, or component rendered to HTML
+                inside a `<noscript>` tag in the HTML body.
+                If None, then noscript is not rendered.
             html_lang: The language of the HTML document.
             settings:
                 Global ReactPy configuration settings that affect behavior and performance. Most settings
@@ -78,6 +86,7 @@ def __init__(
         self.extra_headers = http_headers or {}
         self.dispatcher_pattern = re.compile(f"^{self.dispatcher_path}?")
         self.html_head = html_head or html.head()
+        self.html_noscript = html_noscript
         self.html_lang = html_lang
 
     def match_dispatch_path(self, scope: AsgiWebsocketScope) -> bool:  # nocov
@@ -97,6 +106,7 @@ class ReactPyPyscriptApp(ReactPyApp):
     def render_index_html(self) -> None:
         """Process the index.html and store the results in this class."""
         head_content = vdom_head_to_html(self.parent.html_head)
+        noscript = html_noscript_to_html(self.parent.html_noscript)
         pyscript_setup = pyscript_setup_html(
             extra_py=self.parent.extra_py,
             extra_js=self.parent.extra_js,
@@ -114,6 +124,7 @@ def render_index_html(self) -> None:
             f'<html lang="{self.parent.html_lang}">'
             f"{head_content}"
             "<body>"
+            f"{noscript}"
             f"{pyscript_component}"
             "</body>"
             "</html>"

diff --git a/src/reactpy/executors/asgi/standalone.py b/src/reactpy/executors/asgi/standalone.py
@@ -7,6 +7,7 @@
 from datetime import UTC, datetime
 from email.utils import formatdate
 from logging import getLogger
+from pathlib import Path
 from typing import Literal, Unpack, cast, overload
 
 from asgi_tools import ResponseHTML
@@ -24,8 +25,13 @@
     AsgiWebsocketScope,
 )
 from reactpy.executors.pyscript.utils import pyscript_setup_html
-from reactpy.executors.utils import server_side_component_html, vdom_head_to_html
+from reactpy.executors.utils import (
+    html_noscript_to_html,
+    server_side_component_html,
+    vdom_head_to_html,
+)
 from reactpy.types import (
+    Component,
     PyScriptOptions,
     ReactPyConfig,
     RootComponentConstructor,
@@ -45,6 +51,11 @@ def __init__(
         *,
         http_headers: dict[str, str] | None = None,
         html_head: VdomDict | None = None,
+        html_noscript: str
+        | Path
+        | Component
+        | RootComponentConstructor
+        | None = "Enable JavaScript to view this site.",
         html_lang: str = "en",
         pyscript_setup: bool = False,
         pyscript_options: PyScriptOptions | None = None,
@@ -56,6 +67,8 @@ def __init__(
             root_component: The root component to render. This app is typically a single page application.
             http_headers: Additional headers to include in the HTTP response for the base HTML document.
             html_head: Additional head elements to include in the HTML response.
+            html_noscript: String, Path to an HTML file, or component rendered to HTML
+                inside a `<noscript>` tag in the HTML body.
             html_lang: The language of the HTML document.
             pyscript_setup: Whether to automatically load PyScript within your HTML head.
             pyscript_options: Options to configure PyScript behavior.
@@ -66,6 +79,7 @@ def __init__(
         self.extra_headers = http_headers or {}
         self.dispatcher_pattern = re.compile(f"^{self.dispatcher_path}?")
         self.html_head = html_head or html.head()
+        self.html_noscript = html_noscript
         self.html_lang = html_lang
 
         if pyscript_setup:
@@ -229,11 +243,13 @@ async def __call__(
 
     def render_index_html(self) -> None:
         """Process the index.html and store the results in this class."""
+        noscript = html_noscript_to_html(self.parent.html_noscript)
         self._index_html = (
             "<!doctype html>"
             f'<html lang="{self.parent.html_lang}">'
             f"{vdom_head_to_html(self.parent.html_head)}"
             "<body>"
+            f"{noscript}"
             f"{server_side_component_html(element_id='app', class_='', component_path='')}"
             "</body>"
             "</html>"

diff --git a/src/reactpy/executors/utils.py b/src/reactpy/executors/utils.py
@@ -2,6 +2,7 @@
 
 import logging
 from collections.abc import Iterable
+from pathlib import Path
 from typing import Any
 
 from reactpy._option import Option
@@ -12,7 +13,7 @@
     REACTPY_RECONNECT_MAX_INTERVAL,
     REACTPY_RECONNECT_MAX_RETRIES,
 )
-from reactpy.types import ReactPyConfig, VdomDict
+from reactpy.types import Component, ReactPyConfig, RootComponentConstructor, VdomDict
 from reactpy.utils import import_dotted_path, reactpy_to_string
 
 logger = logging.getLogger(__name__)
@@ -46,6 +47,20 @@ def vdom_head_to_html(head: VdomDict) -> str:
     raise ValueError("Head element must be constructed with `html.head`.")
 
 
+def html_noscript_to_html(
+    html_noscript: str | Path | VdomDict | Component | RootComponentConstructor | None,
+) -> str:
+    if html_noscript is None:
+        return ""
+    if isinstance(html_noscript, Path):
+        html_noscript = html_noscript.read_text()
+    elif callable(html_noscript):
+        html_noscript = reactpy_to_string(html_noscript())
+    elif isinstance(html_noscript, dict):
+        html_noscript = reactpy_to_string(html_noscript)
+    return f"<noscript>{html_noscript}</noscript>"
+
+
 def process_settings(settings: ReactPyConfig) -> None:
     """Process the settings and return the final configuration."""
     from reactpy import config

diff --git a/tests/test_asgi/test_pyscript.py b/tests/test_asgi/test_pyscript.py
@@ -1,16 +1,20 @@
 # ruff: noqa: S701
+import asyncio
 from pathlib import Path
 
 import pytest
 from jinja2 import Environment as JinjaEnvironment
 from jinja2 import FileSystemLoader as JinjaFileSystemLoader
+from requests import request
 from starlette.applications import Starlette
 from starlette.routing import Route
 from starlette.templating import Jinja2Templates
 
+import reactpy
 from reactpy import html
 from reactpy.executors.asgi.pyscript import ReactPyCsr
 from reactpy.testing import BackendFixture, DisplayFixture
+from reactpy.testing.common import REACTPY_TESTS_DEFAULT_TIMEOUT
 
 
 @pytest.fixture(scope="module")
@@ -98,6 +102,156 @@ def test_bad_file_path():
         ReactPyCsr()
 
 
+async def test_customized_noscript(tmp_path: Path):
+    noscript_file = tmp_path / "noscript.html"
+    noscript_file.write_text(
+        '<p id="noscript-message">Please enable JavaScript.</p>',
+        encoding="utf-8",
+    )
+
+    app = ReactPyCsr(
+        Path(__file__).parent / "pyscript_components" / "root.py",
+        html_noscript=noscript_file,
+    )
+
+    async with BackendFixture(app) as server:
+        url = f"http://{server.host}:{server.port}"
+        response = await asyncio.to_thread(
+            request, "GET", url, timeout=REACTPY_TESTS_DEFAULT_TIMEOUT.current
+        )
+        assert response.status_code == 200
+        assert (
+            '<noscript><p id="noscript-message">Please enable JavaScript.</p></noscript>'
+            in response.text
+        )
+
+
+
+async def test_customized_noscript_string():
+    app = ReactPyCsr(
+        Path(__file__).parent / "pyscript_components" / "root.py",
+        html_noscript='<p id="noscript-message">Please enable JavaScript.</p>',
+    )
+
+    async with BackendFixture(app) as server:
+        url = f"http://{server.host}:{server.port}"
+        response = await asyncio.to_thread(
+            request, "GET", url, timeout=REACTPY_TESTS_DEFAULT_TIMEOUT.current
+        )
+        assert response.status_code == 200
+        assert (
+            '<noscript><p id="noscript-message">Please enable JavaScript.</p></noscript>'
+            in response.text
+        )
+
+
+async def test_customized_noscript_from_file(tmp_path: Path):
+    noscript_file = tmp_path / "noscript.html"
+    noscript_file.write_text(
+        '<p id="noscript-message">Please enable JavaScript.</p>',
+        encoding="utf-8",
+    )
+
+    app = ReactPyCsr(
+        Path(__file__).parent / "pyscript_components" / "root.py",
+        html_noscript=noscript_file,
+    )
+
+    async with BackendFixture(app) as server:
+        url = f"http://{server.host}:{server.port}"
+        response = await asyncio.to_thread(
+            request, "GET", url, timeout=REACTPY_TESTS_DEFAULT_TIMEOUT.current
+        )
+        assert response.status_code == 200
+        assert (
+            '<noscript><p id="noscript-message">Please enable JavaScript.</p></noscript>'
+            in response.text
+        )
+
+
+async def test_customized_noscript_from_string():
+    app = ReactPyCsr(
+        Path(__file__).parent / "pyscript_components" / "root.py",
+        html_noscript='<p id="noscript-message">Please enable JavaScript.</p>',
+    )
+
+    async with BackendFixture(app) as server:
+        url = f"http://{server.host}:{server.port}"
+        response = await asyncio.to_thread(
+            request, "GET", url, timeout=REACTPY_TESTS_DEFAULT_TIMEOUT.current
+        )
+        assert response.status_code == 200
+        assert (
+            '<noscript><p id="noscript-message">Please enable JavaScript.</p></noscript>'
+            in response.text
+        )
+
+
+async def test_customized_noscript_from_component():
+    @reactpy.component
+    def noscript_message():
+        return html.p({"id": "noscript-message"}, "Please enable JavaScript.")
+
+    app = ReactPyCsr(
+        Path(__file__).parent / "pyscript_components" / "root.py",
+        html_noscript=noscript_message,
+    )
+
+    async with BackendFixture(app) as server:
+        url = f"http://{server.host}:{server.port}"
+        response = await asyncio.to_thread(
+            request, "GET", url, timeout=REACTPY_TESTS_DEFAULT_TIMEOUT.current
+        )
+        assert response.status_code == 200
+        assert (
+            '<noscript><p id="noscript-message">Please enable JavaScript.</p></noscript>'
+            in response.text
+        )
+
+
+async def test_default_noscript_rendered():
+    app = ReactPyCsr(Path(__file__).parent / "pyscript_components" / "root.py")
+
+    async with BackendFixture(app) as server:
+        url = f"http://{server.host}:{server.port}"
+        response = await asyncio.to_thread(
+            request, "GET", url, timeout=REACTPY_TESTS_DEFAULT_TIMEOUT.current
+        )
+        assert response.status_code == 200
+        assert "<noscript>Enable JavaScript to view this site.</noscript>" in response.text
+
+
+
+async def test_noscript_omitted():
+    app = ReactPyCsr(Path(__file__).parent / "pyscript_components" / "root.py")
+
+    async with BackendFixture(app) as server:
+        url = f"http://{server.host}:{server.port}"
+        response = await asyncio.to_thread(
+            request, "GET", url, timeout=REACTPY_TESTS_DEFAULT_TIMEOUT.current
+        )
+        assert response.status_code == 200
+        assert (
+            "<noscript>Enable JavaScript to view this site.</noscript>"
+            in response.text
+        )
+
+
+async def test_noscript_disabled():
+    app = ReactPyCsr(
+        Path(__file__).parent / "pyscript_components" / "root.py",
+        html_noscript=None,
+    )
+
+    async with BackendFixture(app) as server:
+        url = f"http://{server.host}:{server.port}"
+        response = await asyncio.to_thread(
+            request, "GET", url, timeout=REACTPY_TESTS_DEFAULT_TIMEOUT.current
+        )
+        assert response.status_code == 200
+        assert "<noscript>" not in response.text
+
+
 async def test_jinja_template_tag(jinja_display: DisplayFixture):
     await jinja_display.goto("/")