Component development with ladle and next/image

#ladle #nextjs #react #typescript

Sometimes it is easier to build a component in isolation than in the place where it will be used.
It is much easier to test all variations and edge cases of the component.
There are tools out there which can help us to build our components in isolation.
The most famous is Storybook,
but I like to use Ladle.
Ladle is much smaller than Storybook and it is built for speed.
In this post we will set up Ladle and
we will learn how we can use next/image within Ladle.

Setup

First we have to install Ladle:

# with pnpm
pnpm add -D @ladle/react
# with yarn
yarn add -D @ladle/react
# with npm
npm install --save-dev @ladle/react

And for most installations, that's it.
Ladle has a useful default configuration,
you only need to create a configuration if your installation differs from the default.
But for most Next.js installations the default does not fit.
Ladle expects stories and components in the "src" folder,
but in many Next.js installations they are in a folder called components.
So we have to create a configuration at .ladle/config.mjs:

export default {
  stories: "components/**/*.stories.{js,jsx,ts,tsx}",
};

With this configuration ladle is able to find our stories.
A good time to write our first story.

First Story

We want to create our first Story for the following component.

type Props = {
  src: string;
  alt: string;
  size?: "sm" | "md" | "lg" | "xl";
};

const sizes = {
  sm: 16,
  md: 32,
  lg: 64,
  xl: 128,
};

const Avatar = ({ src, alt, size = "md" }: Props) => (
  <img
    className="rounded-full shadow-md ring-2 ring-zinc-300 dark:ring-zinc-700"
    src={src}
    width={sizes[size]}
    height={sizes[size]}
    alt={alt}
  />
);

export default Avatar;

We want to create a story which shows us all sizes of the Avatar component next to each other.
To create a new story we have to create a story file next to our component:

import Avatar from "./Avatar";

export const Default = () => <Avatar src="https://robohash.org/sdorra.dev" alt="Robohash of sdorra.dev" />;

export const Sizes = () => (
  <div className="flex gap-4">
    <Avatar src="https://robohash.org/sdorra.dev" alt="Robohash of sdorra.dev" size="sm" />
    <Avatar src="https://robohash.org/sdorra.dev" alt="Robohash of sdorra.dev" size="md" />
    <Avatar src="https://robohash.org/sdorra.dev" alt="Robohash of sdorra.dev" size="lg" />
    <Avatar src="https://robohash.org/sdorra.dev" alt="Robohash of sdorra.dev" size="xl" />
  </div>
);

Now it is time to start Ladle.

# with pnpm
pnpm ladle dev
# with yarn
yarn ladle dev
# with npm
npm ladle dev

Ladle should show 2 stories below Avatar.
Default which shows our component within its default size and
Sizes which shows the component in all available sizes next to each other.

Bonus:

With a little bit of typescript magic, we can avoid the duplicate definitions of the sizes.

// we export sizes so that we can reuse it in our story
export const sizes = {
  sm: 16,
  md: 32,
  lg: 64,
  xl: 128,
};

// we can infer the union type of Size from the sizes object
export type Size = keyof typeof sizes;

type Props = {
  src: string;
  alt: string;
  // we can use our inferred type
  size?: Size;
};

const Avatar = ({ src, alt, size = "md" }: Props) => (
  <img
    className="rounded-full shadow-md ring-2 ring-zinc-300 dark:ring-zinc-700"
    src={src}
    width={sizes[size]}
    height={sizes[size]}
    alt={alt}
  />
);

export default Avatar;

import Avatar, { sizes } from "./Avatar";

export const Default = () => (
  <Avatar src="https://robohash.org/sdorra.dev" alt="Robohash of sdorra.dev" />
);

// We can now create an array of sizes from the exported object.
// Unfortunately we have to cast the array using `as`,
// because `Object.keys` only returns `string[]`.
// https://github.com/Microsoft/TypeScript/issues/12870
const sizeKeys = Object.keys(sizes) as Size[];

export const Sizes = () => (
  <div className="flex gap-4">
    {/* We can loop over the array of sizes */}
    {sizeKeys.map(size) => (
      <Avatar key={size} src="https://robohash.org/sdorra.dev" alt="Robohash of sdorra.dev" size={size} />
    )}
  </div>
);

next/image

After we got Ladle running and wrote our first story,
we want to develop our component further.
We want to use next/image instead of img to get all the advantages of next/image.
So we just replace the img tag with the Image tag from next/image.

import Image from "next/image";

// Types and props remain unchanged

const Avatar = ({ src, alt, size = "md" }: Props) => (
  <Image
    className="rounded-full shadow-md ring-2 ring-zinc-300 dark:ring-zinc-700"
    src={src}
    width={sizes[size]}
    height={sizes[size]}
    alt={alt}
  />
);

But now we get an error in ladle.

Error: Uncaught ReferenceError: process is not defined

After a short research session I found the following issue on GitHub.

https://github.com/tajo/ladle/issues/100

One of the comments provided the following solution.
We have to create a file called vite.config.ts in the root of our project.

import { defineConfig } from "vite";

export default defineConfig({
  define: {
    "process.env": process.env,
  },
});

That fixes the process is not defined error,
but we immediately get the next error.

Error:
Uncaught Error: Invalid src prop (https://robohash.org/sdorra.dev) on next/image, hostname "robohash.org" is not
configured under images in your next.config.js See more info:
https://nextjs.org/docs/messages/next-image-unconfigured-host

All right, but we don't want to add the entry to next.config.js at all,
since this is just test data and besides,
we still get the same error when we make the entry.

After another look at issue #100,
we can tell next/image that it should skip the optimization if the component is rendered in Ladle.
That is fine, because the bandwidth does not play a big role during the development.
With the following code placed inside .ladle/components.tsx ...

import * as NextImage from "next/image";

const OriginalNextImage = NextImage.default;

Object.defineProperty(NextImage, "default", {
  configurable: true,
  value: (props) => <OriginalNextImage {...props} unoptimized />,
});

... we can add the unoptimized to each usage of next/image.
Great, that fixed our problem.
But unfortunately only in the development mode of Ladle.
If we run the production build (ladle build and ladle preview), we get the next error.

Error: Uncaught TypeError: Cannot redefine property: default

Our solution does not work with the production build, we have to find another solution.

The solution

Fortunately, I thought of another way to get the unoptimized prop to all image instances.
We can create an alias for the next/image import and resolve next/image to a custom component.
This can be done in the vite.config.ts:

import path from "path";
import { defineConfig } from "vite";

export default defineConfig({
  resolve: {
    alias: {
      "next/image": path.resolve(__dirname, "./UnoptimizedImage.tsx"),
    },
  },
  define: {
    "process.env": process.env,
  },
});

Now we can write our own image component to UnoptimizedImage.tsx.
But what if we want to use the original next/image in our component?
In order to achieve this we can define another alias in the vite.config.ts:

import path from "path";
import { defineConfig } from "vite";

export default defineConfig({
  resolve: {
    alias: {
      "next/original-image": require.resolve("next/image"),
      "next/image": path.resolve(__dirname, "./.ladle/UnoptimizedImage.tsx"),
    },
  },
  define: {
    "process.env": process.env,
  },
});

Now we should have everything together to make our UnoptimizedImage.

import React from "react";
// @ts-ignore have a look in vite.config.ts
import OriginalImage from "next/original-image";

const UnoptimizedImage = (props: any) => {
  return <OriginalImage {...props} unoptimized />;
};

export default UnoptimizedImage;

After that we only have to remove the workaround from .ladle/components.tsx or
we can remove the complete file if it has no other content.
After a quick look into Ladle (production and development mode),
we can see that we have finally solved the problem.