This package contains simple utility functions to use with Remix.run.

npm install remix-utils remix @remix-run/node @remix-run/react react

The promiseHash function is not directly related to Remix but it's a useful function when working with loaders and actions.

This function is an object version of Promise.all which lets you pass an object with promises and get an object with the same keys with the resolved values.

export let loader: LoaderFunction = async ({ request }) => {
  return json(
    promiseHash({
      user: getUser(request),
      posts: getPosts(request),
    })
  );
};

You can use nested promiseHash to get a nested object with resolved values.

export let loader: LoaderFunction = async ({ request }) => {
  return json(
    promiseHash({
      user: getUser(request),
      posts: promiseHash({
        list: getPosts(request),
        comments: promiseHash({
          list: getComments(request),
          likes: getLikes(request),
        }),
      }),
    })
  );
};

Note This can only be run inside entry.client.

This function lets you easily cache inside the browser's Cache Storage every JS file built by Remix.

To use it, open your entry.client file and add this:

import { cacheAssets } from "remix-utils";

cacheAssets().catch((error) => {
  // do something with the error, or not
});

The function receives an optional options object with two options:

• cacheName is the name of the Cache object to use, the default value is assets.
• buildPath is the pathname prefix for all Remix built assets, the default value is /build/ which is the default build path of Remix itself.

It's important that if you changed your build path in remix.config.js you pass the same value to cacheAssets or it will not find your JS files.

The cacheName can be left as is unless you're adding a Service Worker to your app and want to share the cache.

cacheAssests({ cacheName: "assets", buildPath: "/build/" }).catch((error) => {
  // do something with the error, or not
});

The ClientOnly component lets you render the children element only on the client-side, avoiding rendering it the server-side.

You can provide a fallback component to be used on SSR, and while optional, it's highly recommended to provide one to avoid content layout shift issues.

import { ClientOnly } from "remix-utils";

export default function View() {
  return (
    <ClientOnly fallback={<SimplerStaticVersion />}>
      {() => <ComplexComponentNeedingBrowserEnvironment />}
    </ClientOnly>
  );
}

This component is handy when you have some complex component that needs a browser environment to work, like a chart or a map. This way, you can avoid rendering it server-side and instead use a simpler static version like an SVG or even a loading UI.

The rendering flow will be:

• SSR: Always render the fallback.
• CSR First Render: Always render the fallback.
• CSR Update: Update to render the actual component.
• CSR Future Renders: Always render the actual component, don't bother to render the fallback.

This component uses the useHydrated hook internally.

The CORS function let you implement CORS headers on your loaders and actions so you can use them as an API for other client-side applications.

There are two main ways to use the cors function.

1. Use it on each loader/action where you want to enable it.
2. Use it globally on entry.server handleDataRequest export.

If you want to use it on every loader/action, you can do it like this:

export let loader: LoaderFunction = async ({ request }) => {
  let data = await getData(request);
  let response = json<LoaderData>(data);
  return await cors(request, response);
};

You could also do the json and cors call in one line.

export let loader: LoaderFunction = async ({ request }) => {
  let data = await getData(request);
  return await cors(request, json<LoaderData>(data));
};

And because cors mutates the response, you can also call it and later return.

export let loader: LoaderFunction = async ({ request }) => {
  let data = await getData(request);
  let response = json<LoaderData>(data);
  await cors(request, response); // this mutates the Response object
  return response; // so you can return it here
};

If you want to setup it globally once, you can do it like this in entry.server

export let handleDataRequest: HandleDataRequestFunction = async (
  response,
  { request }
) => {
  return await cors(request, response);
};

Additionally, the cors function accepts a options object as a third optional argument. These are the options.

• origin: Configures the Access-Control-Allow-Origin CORS header. Possible values are:
  • true: Enable CORS for any origin (same as "*")
  • false: Don't setup CORS
  • string: Set to a specific origin, if set to "*" it will allow any origin
  • RegExp: Set to a RegExp to match against the origin
  • Array<string | RegExp>: Set to an array of origins to match against the string or RegExp
  • Function: Set to a function that will be called with the request origin and should return a boolean indicating if the origin is allowed or not. The default value is true.
• methods: Configures the Access-Control-Allow-Methods CORS header. The default value is ["GET", "HEAD", "PUT", "PATCH", "POST", "DELETE"].
• allowedHeaders: Configures the Access-Control-Allow-Headers CORS header.
• exposedHeaders: Configures the Access-Control-Expose-Headers CORS header.
• credentials: Configures the Access-Control-Allow-Credentials CORS header.
• maxAge: Configures the Access-Control-Max-Age CORS header.

The CSRF related functions let you implement CSRF protection on your application.

This part of Remix Utils needs React and server-side code.

In the server, we need to add to our root component the following.

import type { LoaderFunction } from "remix";
import { createAuthenticityToken, json } from "remix-utils";
import { getSession, commitSession } from "~/services/session.server";

interface LoaderData {
  csrf: string;
}

export let loader: LoaderFunction = async ({ request }) => {
  let session = await getSession(request.headers.get("cookie"));
  let token = createAuthenticityToken(session);
  return json<LoaderData>(
    { csrf: token },
    { headers: { "Set-Cookie": await commitSession(session) } }
  );
};

The createAuthenticityToken function receives a session object and stores the authenticity token there using the csrf key (you can pass the key name as a second argument). Finally, you need to return the token in a json response and commit the session.

You need to read the authenticity token and render the AuthenticityTokenProvider component wrapping your code in your root.

import { Outlet, useLoaderData } from "remix";
import { Document } from "~/components/document";

export default function Root() {
  let { csrf } = useLoaderData<LoaderData>();
  return (
    <AuthenticityTokenProvider token={csrf}>
      <Document>
        <Outlet />
      </Document>
    </AuthenticityTokenProvider>
  );
}

With this, your whole app can access the authenticity token generated in the root.

When you create a form in some route, you can use the AuthenticityTokenInput component to add the authenticity token to the form.

import { Form } from "remix";
import { AuthenticityTokenInput } from "remix-utils";

export default function SomeRoute() {
  return (
    <Form method="post">
      <AuthenticityTokenInput />
      <input type="text" name="something" />
    </Form>
  );
}

Note that the authenticity token is only really needed for a form that mutates the data somehow. If you have a search form making a GET request, you don't need to add the authenticity token there.

This AuthenticityTokenInput will get the authenticity token from the AuthenticityTokenProvider component and add it to the form as the value of a hidden input with the name csrf. You can customize the field name using the name prop.

<AuthenticityTokenInput name="customName" />

You should only customize the name if you also changed it on createAuthenticityToken.

If you need to use useFetcher (or useSubmit) instead of Form you can also get the authenticity token with the useAuthenticityToken hook.

import { useFetcher } from "remix";
import { useAuthenticityToken } from "remix-utils";

export function useMarkAsRead() {
  let fetcher = useFetcher();
  let csrf = useAuthenticityToken();
  return function submit(data) {
    fetcher.submit({ csrf, ...data }, { action: "/action", method: "post" });
  };
}

Finally, you need to verify the authenticity token in the action that received the request.

import type { ActionFunction } from "remix";
import { verifyAuthenticityToken, redirectBack } from "remix-utils";
import { getSession, commitSession } from "~/services/session.server";

export let action: ActionFunction = async ({ request }) => {
  let session = await getSession(request.headers.get("Cookie"));
  await verifyAuthenticityToken(request, session);
  // do something here
  return redirectBack(request, { fallback: "/fallback" });
};

Suppose the authenticity token is missing on the session, the request body, or doesn't match. In that case, the function will throw an Unprocessable Entity response that you can either catch and handle manually or let pass and render your CatchBoundary.

If you need to create <link /> tags based on the loader data instead of being static, you can use the DynamicLinks component together with the DynamicLinksFunction type.

In the route you want to define dynamic links add handle export with a dynamicLinks method, this method should implement the DynamicLinksFunction type.

// create the dynamicLinks function with the correct type
// note: loader type is optional
let dynamicLinks: DynamicLinksFunction<SerializeFrom<typeof loader>> = ({
  id,
  data,
  params,
  location,
  parentsData,
}) => {
  if (!data.user) return [];
  return [{ rel: "preload", href: data.user.avatar, as: "image" }];
};

// and export it through the handle, you could also create it inline here
// if you don't care about the type
export let handle = { dynamicLinks };

Then, in the root route, add the DynamicLinks component before the Remix's Links component, usually inside a Document component.

import { Links, LiveReload, Meta, Scripts, ScrollRestoration } from "remix";
import { DynamicLinks } from "remix-utils";

type Props = { children: React.ReactNode; title?: string };

export function Document({ children, title }: Props) {
  return (
    <html lang="en">
      <head>
        <meta charSet="utf-8" />
        <meta name="viewport" content="width=device-width,initial-scale=1" />
        {title ? <title>{title}</title> : null}
        <Meta />
        <DynamicLinks />
        <Links />
      </head>
      <body>
        {children}
        <ScrollRestoration />
        <Scripts />
        <LiveReload />
      </body>
    </html>
  );
}

Now, any link you defined in the DynamicLinksFunction will be added to the HTML as any static link in your LinksFunctions.

Note You can also put the DynamicLinks after the Links component, it's up to you what to prioritize, since static links are probably prefetched when you do <Link prefetch> you may want to put the DynamicLinks first to prioritize them.

If you need to load different external scripts on certain routes, you can use the ExternalScripts component together with the ExternalScriptsFunction type.

In the route you want to load the script add a handle export with a scripts method, this method should implement the ExternalScriptsFunction type.

// create the scripts function with the correct type
// note: loader type is optional
let scripts: ExternalScriptsFunction<SerializeFrom<typeof loader>> = ({
  id,
  data,
  params,
  location,
  parentsData,
}) => {
  return [
    {
      src: "https://code.jquery.com/jquery-3.6.0.min.js",
      integrity: "sha256-/xUj+3OJU5yExlq6GSYGSHk7tPXikynS7ogEvDej/m4=",
      crossOrigin: "anonymous",
    },
  ];
};

// and export it through the handle, you could also create it inline here
// if you don't care about the type
export let handle = { scripts };

Then, in the root route, add the ExternalScripts component together with the Remix's Scripts component, usually inside a Document component.

import { Links, LiveReload, Meta, Scripts, ScrollRestoration } from "remix";
import { ExternalScripts } from "remix-utils";

type Props = { children: React.ReactNode; title?: string };

export function Document({ children, title }: Props) {
  return (
    <html lang="en">
      <head>
        <meta charSet="utf-8" />
        <meta name="viewport" content="width=device-width,initial-scale=1" />
        {title ? <title>{title}</title> : null}
        <Meta />
        <Links />
      </head>
      <body>
        {children}
        <ScrollRestoration />
        <ExternalScripts />
        <Scripts />
        <LiveReload />
      </body>
    </html>
  );
}

Now, any script you defined in the ScriptsFunction will be added to the HTML together with a <link rel="preload"> before it.

Tip: You could use it together with useShouldHydrate to disable Remix scripts in certain routes but still load scripts for analytics or small features that need JS but don't need the full app JS to be enabled.

If you need to include structured data (JSON-LD) scripts on certain routes, you can use the StructuredData component together with the HandleStructuredData type or StructuredDataFunction type.

In the route you want to include the structured data, add a handle export with a structuredData method, this method should implement the StructuredDataFunction type.

import type { WithContext, BlogPosting } from "schema-dts";

// create the structuredData function with the correct type
// note: loader type is optional
let structuredData: StructuredDataFunction<
  SerializeFrom<typeof loader>,
  BlogPosting
> = ({ id, data, params, location, parentsData }) => {
  let { post } = data;

  return {
    "@context": "https://schema.org",
    "@type": "BlogPosting",
    datePublished: post.published,
    mainEntityOfPage: {
      "@type": "WebPage",
      "@id": post.postUrl,
    },
    image: post.featuredImage,
    author: {
      "@type": "Person",
      name: post.authorName,
    },
  };
};

// and export it through the handle, you could also create it inline here
// if you don't care about the type or using the `HandleStructuredData` type
export let handle = { structuredData };

Then, in the root route, add the StructuredData component together with the Remix's Scripts component, usually inside a Document component.

import { Links, LiveReload, Meta, Scripts, ScrollRestoration } from "remix";
import { StructuredData } from "remix-utils";

type Props = { children: React.ReactNode; title?: string };

export function Document({ children, title }: Props) {
  return (
    <html lang="en">
      <head>
        <meta charSet="utf-8" />
        <meta name="viewport" content="width=device-width,initial-scale=1" />
        {title ? <title>{title}</title> : null}
        <Meta />
        <Links />
        <StructuredData />
      </head>
      <body>
        {children}
        <ScrollRestoration />
        <Scripts />
        <LiveReload />
      </body>
    </html>
  );
}

Now, any structured data you defined in the StructuredDataFunction will be added to the HTML, in the head. You may choose to include the <StructuredData /> in either the head or the body, both are valid.

This hook lets you trigger a refresh of the loaders in the current URL.

The way this works is by sending a fetcher.submit to /dev/null to trigger all loaders to run.

You need to create app/routes/dev/null.ts and define an action that returns null.

// app/routes/dev/null.ts
export function action() {
  return null;
}

This Hook is mostly useful if you want to trigger the refresh manually from an effect, examples of this are:

• Set an interval to trigger the refresh
• Refresh when the browser tab is focused again
• Refresh when the user is online again

import { useDataRefresh } from "remix-utils";

function useDataRefreshOnInterval() {
  let { refresh } = useDataRefresh();
  useEffect(() => {
    let interval = setInterval(refresh, 5000);
    return () => clearInterval(interval);
  }, [refresh]);
}

The return value of useDataRefresh is an object with the following keys:

• refresh: a function that trigger the refresh
• type: a string which can be init, refreshRedirect or refresh
• status: a string which can be loading or idle

This hook lets you know if the global transition or if one of any active fetchers is either loading or submitting.

import { useGlobalPendingState } from "remix-utils";

export function GlobalPendingUI() {
  let globalState = useGlobalPendingState();

  if (globalState === "idle") return null;
  return <Spinner />;
}

The return value of useGlobalPendingState is either "idle" or "pending".

This hook lets you detect if your component is already hydrated. This means the JS for the element loaded client-side and React is running.

With useHydrated, you can render different things on the server and client while ensuring the hydration will not have a mismatched HTML.

import { useHydrated } from "remix-utils";

export function Component() {
  let isHydrated = useHydrated();

  if (isHydrated) {
    return <ClientOnlyComponent />;
  }

  return <ServerFallback />;
}

When doing SSR, the value of isHydrated will always be false. The first client-side render isHydrated will still be false, and then it will change to true.

After the first client-side render, future components rendered calling this hook will receive true as the value of isHydrated. This way, your server fallback UI will never be rendered on a route transition.

This hooks lets you get the locales returned by the root loader. It follows a simple convention, your root loader return value should be an objet with the key locales.

You can combine it with getClientLocal to get the locales on the root loader and return that. The return value of useLocales is a Locales type which is string | string[] | undefined.

// in the root loader
export let loader: LoaderFunction = async ({ request }) => {
  let locales = getClientLocales(request);
  return json({ locales });
};

// in any route (including root!)
export default function Screen() {
  let locales = useLocales();
  let date = new Date();
  let dateTime = date.toISOString;
  let formattedDate = date.toLocaleDateString(locales, options);
  return <time dateTime={dateTime}>{formattedDate}</time>;
}

The return type of useLocales is ready to be used with the Intl API.

This hook lets you access the data of any route in the current page. This can include child or parent routes.

To use it, call useRouteData in your component and pass the route ID as a string. As an example, if you had the following routes:

routes/articles/$slug.tsx
routes/articles/index.tsx
routes/articles.tsx

Then you need to pass useRouteData("routes/articles") to get the data of routes/articles.tsx, useRouteData("routes/articles/index") to get the data of routes/articles/index.tsx and routes/articles/$slug to get the data of routes/articles/$slug.tsx.

As you can see, the ID is the route file without the extension.

let parentData = useRouteData("routes/articles");
let indexData = useRouteData("routes/articles/index");

The useRouteData hook receives a generic to be used as the type of the route data. Because the route may not be found the return type is Data | undefined. This means if you do the following:

let data = useRouteData<ArticleShowData>("routes/articles");

The type of data will be ArticleShowData | undefined, so you will need to check if it's not undefined before being able to use it.

If you are building a Remix application where most routes are static, and you want to avoid loading client-side JS, you can use this hook, plus some conventions, to detect if one or more active routes needs JS and only render the Scripts component in that case.

In your document component, you can call this hook to dynamically render the Scripts component if needed.

import type { ReactNode } from "react";
import { Links, LiveReload, Meta, Scripts } from "remix";
import { useShouldHydrate } from "remix-utils";

interface DocumentProps {
  children: ReactNode;
  title?: string;
}

export function Document({ children, title }: DocumentProps) {
  let shouldHydrate = useShouldHydrate();
  return (
    <html lang="en">
      <head>
        <meta charSet="utf-8" />
        <link rel="icon" href="/favicon.png" type="image/png" />
        {title ? <title>{title}</title> : null}
        <Meta />
        <Links />
      </head>
      <body>
        {children}
        {shouldHydrate && <Scripts />}
        <LiveReload />
      </body>
    </html>
  );
}

Now, you can export a handle object with the hydrate property as true in any route module.

export let handle = { hydrate: true };

This will mark the route as requiring JS hydration.

In some cases, a route may need JS based on the data the loader returned. For example, if you have a component to purchase a product, but only authenticated users can see it, you don't need JS until the user is authenticated. In that case, you can make hydrate be a function receiving your loader data.

export let handle = {
  hydrate(data: LoaderData) {
    return data.user.isAuthenticated;
  },
};

The useShouldHydrate hook will detect hydrate as a function and call it using the route data.

This function receives a Request or Headers objects and will try to get the IP address of the client (the user) who originated the request.

export let loader: LoaderFunction = async ({ request }) => {
  // using the request
  let ipAddress = getClientIPAddress(request);
  // or using the headers
  let ipAddress = getClientIPAddress(request.headers);
};

If it can't find he ipAddress the return value will be null. Remember to check if it was able to find it before using it.

The function uses the following list of headers, in order of preference:

• X-Client-IP
• X-Forwarded-For
• Fly-Client-IP
• CF-Connecting-IP
• Fastly-Client-Ip
• True-Client-Ip
• X-Real-IP
• X-Cluster-Client-IP
• X-Forwarded
• Forwarded-For
• Forwarded

When a header is found that contains a valid IP address, it will return without checking the other headers.

This function let you get the locales of the client (the user) who originated the request.

export let loader: LoaderFunction = async ({ request }) => {
  // using the request
  let locales = getClientLocales(request);
  // or using the headers
  let locales = getClientLocales(request.headers);
};

The return value is a Locales type, which is string | string[] | undefined.

The returned locales can be directly used on the Intl API when formatting dates, numbers, etc.

import { getClientLocales } from "remix-utils";
export let loader: LoaderFunction = async ({ request }) => {
  let locales = getClientLocales(request);
  let nowDate = new Date();
  let formatter = new Intl.DateTimeFormat(locales, {
    year: "numeric",
    month: "long",
    day: "numeric",
  });
  return json({ now: formatter.format(nowDate) });
};

The value could also be returned by the loader and used on the UI to ensure the user's locales is used on both server and client formatted dates.

This function let you identify if a request was created because of a prefetch triggered by using <Link prefetch="intent"> or <Link prefetch="render">.

This will let you implement a short cache only for prefetch requests so you avoid the double data request.

export let loader: LoaderFunction = async ({ request }) => {
  let data = await getData(request);
  let headers = new Headers();

  if (isPrefetch(request)) {
    headers.set("Cache-Control", "private, max-age=5, smax-age=0");
  }

  return json(data, { headers });
};

This function is a wrapper of the redirect helper from Remix. Unlike Remix's version, this one receives the whole request object as the first value and an object with the response init and a fallback URL.

The response created with this function will have the Location header pointing to the Referer header from the request, or if not available, the fallback URL provided in the second argument.

import { redirectBack } from "remix-utils";
import type { ActionFunction } from "remix";

export let action: ActionFunction = async ({ request }) => {
  await redirectBack(request, { fallback: "/" });
};

This helper is most useful when used in a generic action to send the user to the same URL it was before.

Helper function to create a Created (201) response with a JSON body.

import { created } from "remix-utils";
import type { ActionFunction } from "remix";

export let action: ActionFunction = async ({ request }) => {
  let result = await doSomething(request);
  return created(result);
};

Helper function to create a Bad Request (400) response with a JSON body.

import { badRequest } from "remix-utils";
import type { ActionFunction } from "remix";

export let action: ActionFunction = async () => {
  throw badRequest({ message: "You forgot something in the form." });
};

Helper function to create an Unauthorized (401) response with a JSON body.

import { unauthorized } from "remix-utils";
import type { LoaderFunction } from "remix";

export let loader: LoaderFunction = async () => {
  // usually what you really want is to throw a redirect to the login page
  throw unauthorized({ message: "You need to login." });
};

Helper function to create a Forbidden (403) response with a JSON body.

import { forbidden } from "remix-utils";
import type { LoaderFunction } from "remix";

export let loader: LoaderFunction = async () => {
  throw forbidden({ message: "You don't have access for this." });
};

Helper function to create a Not Found (404) response with a JSON body.

import { notFound } from "remix-utils";
import type { LoaderFunction } from "remix";

export let loader: LoaderFunction = async () => {
  throw notFound({ message: "This doesn't exists." });
};

Helper function to create an Unprocessable Entity (422) response with a JSON body.

import { unprocessableEntity } from "remix-utils";
import type { LoaderFunction } from "remix";

export let loader: LoaderFunction = async () => {
  throw unprocessableEntity({ message: "This doesn't exists." });
};

This is used by the CSRF validation. You probably don't want to use it directly.

Helper function to create a Server Error (500) response with a JSON body.

import { serverError } from "remix-utils";
import type { LoaderFunction } from "remix";

export let loader: LoaderFunction = async () => {
  throw serverError({ message: "Something unexpected happened." });
};

Helper function to create a Not Modified (304) response without a body and any header.

export let loader: LoaderFunction = async ({ request }) => {
  return notModified();
};

Helper function to create a JavaScript file response with any header.

This is useful to create JS files based on data inside a Resource Route.

export let loader: LoaderFunction = async ({ request }) => {
  return javascript("console.log('Hello World')");
};

Helper function to create a CSS file response with any header.

This is useful to create CSS files based on data inside a Resource Route.

export let loader: LoaderFunction = async ({ request }) => {
  return stylesheet("body { color: red; }");
};

Helper function to create a PDF file response with any header.

This is useful to create PDF files based on data inside a Resource Route.

export let loader: LoaderFunction = async ({ request }) => {
  return pdf(await generatePDF(request.formData()));
};

Helper function to create a HTML file response with any header.

This is useful to create HTML files based on data inside a Resource Route.

export let loader: LoaderFunction = async ({ request }) => {
  return html("<h1>Hello World</h1>");
};

Cookie objects in Remix allows any type, the typed cookies from Remix Utils lets you use Zod to parse the cookie values and ensure they conform to a schema.

import { createCookie } from "remix";
import { createTypedCookie } from "remix-utils";
import { z } from "zod";

let cookie = createCookie("returnTo", cookieOptions);
let schema = z.string().url();

// pass the cookie and the schema
let typedCookie = createTypedCookie({ cookie, schema });

// this will be a string and also a URL
let returnTo = await typedCookie.parse(request.headers.get("Cookie"));

// this will not pass the schema validation and throw a ZodError
await cookie.serialize("a random string that's not a URL");
// this will make TS yell because it's not a string, if you ignore it it will
// throw a ZodError
await cookie.serialize(123);

You could also use typed cookies with any sessionStorage mechanism from Remix.

let cookie = createCookie("session", cookieOptions);
let schema = z.object({ token: z.string() });

let sessionStorage = createCookieSessionStorage({
  cookie: createTypedCookie({ cookie, schema }),
});

// if this works then the correct data is stored in the session
let session = sessionStorage.getSession(request.headers.get("Cookie"));

session.unset("token"); // remove a required key from the session

// this will throw a ZodError because the session is missing the required key
await sessionStorage.commitSession(session);

Now Zod will ensure the data you try to save to the session is valid removing any extra field and throwing if you don't set the correct data in the session.

Note The session object is not really typed so doing session.get will not return the correct type, you can do schema.parse(session.data) to get the typed version of the session data.

You can also use async refinements in your schemas because typed cookies uses parseAsync method from Zod.

let cookie = createCookie("session", cookieOptions);

let schema = z.object({
  token: z.string().refine(async (token) => {
    let user = await getUserByToken(token);
    return user !== null;
  }, "INVALID_TOKEN"),
});

let sessionTypedCookie = createTypedCookie({ cookie, schema });

// this will throw if the token stored in the cookie is not valid anymore
sessionTypedCookie.parse(request.headers.get("Cookie"));

Session objects in Remix allows any type, the typed sessions from Remix Utils lets you use Zod to parse the session data and ensure they conform to a schema.

import { createCookieSessionStorage } from "remix";
import { createTypedSessionStorage } from "remix-utils";
import { z } from "zod";

let schema = z.object({
  token: z.string().optiona(),
  count: z.number().default(1),
});

// you can use a Remix's Cookie container or a Remix Utils's Typed Cookie container
let sessionStorage = createCookieSessionStorage({ cookie });

// pass the session storage and the schema
let typedSessionStorage = createTypedSessionStorage({ sessionStorage, schema });

Now you can use typedSessionStorage as a drop-in replacement for your normal sessionStorage.

let session = typedSessionStorage.getSession(request.headers.get("Cookie"));

session.get("token"); // this will be a string or undefined
session.get("count"); // this will be a number
session.get("random"); // this will make TS yell because it's not in the schema

session.has("token"); // this will be a boolean
session.has("count"); // this will be a boolean

// this will make TS yell because it's not a string, if you ignore it it will
// throw a ZodError
session.set("token", 123);

Now Zod will ensure the data you try to save to the session is valid by not allowing you to get, set or unset data.

Note Remember that you either need to mark fields as optional or set a default value in the schema, otherwise it will be impossible to call getSession to get a new session object.

You can also use async refinements in your schemas because typed sesions uses parseAsync method from Zod.

let schema = z.object({
  token: z
    .string()
    .optional()
    .refine(async (token) => {
      if (!token) return true; // handle optionallity
      let user = await getUserByToken(token);
      return user !== null;
    }, "INVALID_TOKEN"),
});

let typedSessionStorage = createTypedSessionStorage({ sessionStorage, schema });

// this will throw if the token stored in the session is not valid anymore
typedSessionStorage.getSession(request.headers.get("Cookie"));

Server-Sent Events are a way to send data from the server to the client without the need for the client to request it. This is useful for things like chat applications, live updates, and more.

There are two utils provided to help with the usage inside Remix:

• eventStream
• useEventSource

The eventStream function is used to create a new event stream response needed to send events to the client.

import { eventStream } from "remix-utils";

export async function loader({ request }: LoaderArgs) {
  return eventStream(request.signal, function setup(send) {
    let timer = setInterval(() => {
      send({ event: "time", data: new Date().toISOString() });
    }, 1000);

    return function clear() {
      clearInterval(timer);
    };
  });
}

Then, inside any component, you can use the useEventSource hook to connect to the event stream.

import { useEventSource } from "remix-utils";

const options = { event: "time" }

function Counter() {
  let time = useEventSource("/sse/time", options);

  if (!time) return null;

  return (
    <time dateTime={time}>
      {new Date(time).toLocaleTimeString("en", {
        minute: "2-digit",
        second: "2-digit",
        hour: "2-digit",
      })}
    </time>
  );
}

The event name in both the event stream and the hook is optional, in which case it will default to message, if defined you must use the same event name in both sides, this also allows you to emit different events from the same event stream.

• Sergio Xalambrí

• MIT License