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
@@ -17,7 +17,7 @@
     pyscript_component_html,
     pyscript_setup_html,
 )
-from reactpy.executors.utils import vdom_head_to_html
+from reactpy.executors.utils import html_noscript_path_to_html, vdom_head_to_html
 from reactpy.types import ReactPyConfig, VdomDict
 
 
@@ -32,6 +32,9 @@ def __init__(
         initial: str | VdomDict = "",
         http_headers: dict[str, str] | None = None,
         html_head: VdomDict | None = None,
+        html_noscript_str_or_path: str
+        | Path
+        | None = "Enable JavaScript to view this site.",
         html_lang: str = "en",
         **settings: Unpack[ReactPyConfig],
     ) -> None:
@@ -59,6 +62,8 @@ 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_str_or_path: String or Path to an HTML file whose contents are rendered within 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 +83,7 @@ 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_str_or_path = html_noscript_str_or_path
         self.html_lang = html_lang
 
     def match_dispatch_path(self, scope: AsgiWebsocketScope) -> bool:  # nocov
@@ -97,6 +103,7 @@ 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_path_to_html(self.parent.html_noscript_str_or_path)
         pyscript_setup = pyscript_setup_html(
             extra_py=self.parent.extra_py,
             extra_js=self.parent.extra_js,
@@ -114,6 +121,7 @@ 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
@@ -24,7 +25,11 @@
     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_path_to_html,
+    server_side_component_html,
+    vdom_head_to_html,
+)
 from reactpy.types import (
     PyScriptOptions,
     ReactPyConfig,
@@ -45,6 +50,9 @@ def __init__(
         *,
         http_headers: dict[str, str] | None = None,
         html_head: VdomDict | None = None,
+        html_noscript_str_or_path: str
+        | Path
+        | None = "Enable JavaScript to view this site.",
         html_lang: str = "en",
         pyscript_setup: bool = False,
         pyscript_options: PyScriptOptions | None = None,
@@ -56,6 +64,8 @@ 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_str_or_path: String or Path to an HTML file whose contents are rendered within 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 +76,7 @@ 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_str_or_path = html_noscript_str_or_path
         self.html_lang = html_lang
 
         if pyscript_setup:
@@ -229,11 +240,13 @@ async def __call__(
 
     def render_index_html(self) -> None:
         """Process the index.html and store the results in this class."""
+        noscript = html_noscript_path_to_html(self.parent.html_noscript_str_or_path)
         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
@@ -46,6 +47,14 @@ def vdom_head_to_html(head: VdomDict) -> str:
     raise ValueError("Head element must be constructed with `html.head`.")
 
 
+def html_noscript_path_to_html(path_or_body: str | Path | None) -> str:
+    if path_or_body is None:
+        return ""
+    if isinstance(path_or_body, Path):
+        return f"<noscript>{path_or_body.read_text()}</noscript>"
+    return f"<noscript>{path_or_body}</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 +102,131 @@ 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_str_or_path=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_str_or_path='<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_str_or_path=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_str_or_path='<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_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_str_or_path=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("/")
 

diff --git a/tests/test_asgi/test_standalone.py b/tests/test_asgi/test_standalone.py
@@ -1,5 +1,6 @@
 import asyncio
 from collections.abc import MutableMapping
+from pathlib import Path
 
 import pytest
 from asgi_tools import ResponseText
@@ -138,6 +139,91 @@ def sample():
             assert (await new_display.page.title()) == custom_title
 
 
+async def test_customized_noscript_from_file(tmp_path: Path):
+    @reactpy.component
+    def sample():
+        return html.h1("Hello World")
+
+    noscript_file = tmp_path / "noscript.html"
+    noscript_file.write_text(
+        '<p id="noscript-message">Please enable JavaScript.</p>',
+        encoding="utf-8",
+    )
+
+    app = ReactPy(
+        sample,
+        html_noscript_str_or_path=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():
+    @reactpy.component
+    def sample():
+        return html.h1("Hello World")
+
+    app = ReactPy(
+        sample,
+        html_noscript_str_or_path='<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_noscript_omitted():
+    @reactpy.component
+    def sample():
+        return html.h1("Hello World")
+
+    app = ReactPy(sample)
+
+    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():
+    @reactpy.component
+    def sample():
+        return html.h1("Hello World")
+
+    app = ReactPy(sample, html_noscript_str_or_path=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_head_request():
     @reactpy.component
     def sample():