Mitosis.js is a compiler device that consumes a common element syntax and outputs framework-specific code. Which means you possibly can write utility performance as soon as and generate it to React, Svelte, or Angular, amongst others. What distinguishes Mitosis from different compile-time frameworks is its “write as soon as, run wherever” method to compilation. Mitosis is a powerful engineering feat, and it has purposes wherever you must summary front-end frameworks into pluggable elements.
Mitosis is a venture from the parents at Builder.io, who additionally developed envelope-stretching tasks just like the Qwik.js framework and Partytown. Builder is itself a superb instance of the sort of utility that advantages from Mitosis. Briefly, Builder means that you can visually design UI layouts throughout numerous underlying framework implementations. It wants a typical language to course of and output these various frameworks, and that language is Mitosis.
Mitosis additionally helps outputting to straight HTML and has Qwik.js on the roadmap. Additionally, Mitosis is the interpretation bridge that Builder makes use of between third-party design device Figma. That’s to say, the abstraction layer is beneficial in taking design output and remodeling it into the specified goal framework.
Itemizing 1 is a straightforward instance that exhibits off a couple of conventions of Mitosis’s JSX variant.
Itemizing 1. Primary listing output in Mitosis (TypeScript)
import useStore from '@builder.io/mitosis'; kind Props = author: string; ; export default perform SongList(props: Props) const state = useStore( songs: [ title: "Strawberry Fields", writer: "John Lennon" , title: "Penny Lane", writer: "Paul McCartney" , title: "Dark Horse", writer: "George Harrison" , title: "It don't come Easy", writer: "Ringo Starr" ], ); return ( <div> <For every=state.songs>(track, index) => <div>track.title</div></For> </div> );
Itemizing 1 takes an inventory of objects (
songs) and outputs a property from each (
track.title). There are few issues to notice on this pattern. First, the file exports a default perform. Due to this fact, it’s defining a useful element. Mitosis will rework this element to the best construction for its goal framework.
Subsequent, word that the element makes use of a hook,
useStore. This hook works analogously to the one present in React. The code then makes use of the state to iterate over the songs with a
<For> element. Iterating over collections is a type of areas of range in frameworks and the
<For> element affords a easy, unified solution to specific it.
Additionally, observe the usual dealing with of element properties, through the
props argument to the perform (with its attendant TypeScript kind definition of
Run the compiler
To place this element by means of the Mitosis compiler (or, strictly talking, transpiler), we are able to arrange a easy Node Bundle Supervisor (NPM) venture. To start out, provoke a venture (
npm init), then set up the Mitosis libraries by coming into
npm set up @builder.io/mitosis-cli @builder.io/mitosis
The Mitosis compiler will robotically discover the information we wish to compile based mostly on a
mitosis.config.js file. We’ll use the easy one proven in Itemizing 2.
Itemizing 2. Mitosis.config.js
module.exports = information: 'src/**', targets: ['vue3', 'solid', 'svelte', 'react', 'angular'], ;
Itemizing 2 tells the place the sources are to be discovered (
src/**) and what output frameworks to make use of.
Our element is in TypeScript, so we’ll want a easy
tsconfig.json file, as properly:
Itemizing 3. tsconfig.js
"compilerOptions": "jsx": "protect", "jsxImportSource": "@builder.io/mitosis"
Itemizing 3 tells the TypeScript command-line interface (
tsc-cli) easy methods to deal with the JSX it encounters. On this case, it leaves the syntax as-is (
protect) and defines the module to make use of for import (
@builder.io/mitosis). See the JSX overview and code pattern within the TypeScript documentation for particulars.
Mitosis with React
Now we’re able to get some output. Run
npm exec mitosis construct. It will drop information into the
output/ listing, one department for every goal framework. Let’s take a peek on the
/output/react/src/elements/Songs.jsx model, which is able to look one thing like Itemizing 4.
Itemizing 4. React model of Songs.jsx
import * as React from "react"; import useState from "react"; perform SongList(props) const [songs, setSongs] = useState(() => [ title: "Strawberry Fields", writer: "John Lennon" , title: "Penny Lane", writer: "Paul McCartney" , title: "Dark Horse", writer: "George Harrison" , title: "It don't come Easy", writer: "Ringo Starr" ]); return /* @__PURE__ */ React.createElement("div", null, songs == null ? void 0 : songs.map((track, index) => /* @__PURE__ */ React.createElement("div", null, track.title))); export SongList as default ;
So, we are able to see that Mitosis has switched to utilizing the React implementation of
useState and has opted for utilizing
React.createElement to outline the
track.map() to iterate over the gathering. It exports the element as a default module. This seems like legitimate React to this point, however let’s test it.
We are able to go to a different listing and spin up a
create-react-app actual fast (see the Create React App web page for particulars), then go to the brand new listing that has simply been created. Within the
/src listing, we’ll copy over the
output/react/src/elements/Songs.jsx file from our Mitosis venture. We open
App.jsx and import the brand new element by including
import “./Songs.jsx” as
Songs, then go into the template markup and use the element someplace with
Now, we are able to run the app with
npm begin. Examine the output at
localhost:3000 and also you’ll see the listing of track names on the web page.
Good. Now we all know that Mitosis is working with React. In a real-world state of affairs, we may readily construct a pipeline so as to add Mitosis to our construct course of.
Mitosis with Svelte
Let’s use a fast shortcut to see how Mitosis works with Svelte. Copy the contents of
/output/svelte/src/elements/Songs.svelte (noticing that Mitosis has given the right extension to the file). Go to the Svelte playground and paste the supply into the left-hand code panel. After a second, you will notice the track listing on the best aspect of the display.
Mitosis is producing appropriate Svelte. In the event you’re curious, Itemizing 5 exhibits the idiomatic Svelte iteration for the
Itemizing 5. Track iterator in Svelte
#every songs as track, index <div>track.title</div> /every And Vue, Angular, SolidJS
You’ll be able to take comparable steps to confirm the correctness of every of the opposite output targets.
Configuration and plugins
Mitosis is meant to be fairly versatile. Specifically, the Mitosis playground demonstrates the flexibility to vary a configuration to pick out not solely completely different frameworks however completely different traits inside them. As an illustration, you possibly can decide a state supplier in React, selecting between
useState, Mobx, and Stable. You can also choose completely different styling options, like Emotion CSS, Styled Elements, and Styled JSX.
Mitosis additionally helps the flexibility to outline plugins that run arbitrary code at strategic moments, like earlier than and after the underlying JSON information construction is generated.
Consuming framework code
You would possibly surprise whether it is doable to flip Mitosis’s performance from producing to consuming framework code. For example, may we take a UI outlined in a framework implementation and parse it into the Mitosis JSON mannequin? That might not solely allow us to two-directionally translate between Mitosis and a framework however really translate between completely different frameworks through the Mitosis mannequin.
I requested Builder.io’s founder, Steve Sewell whether or not Mitosis may perceive framework code. Right here’s what he stated:
[Framework parsing] is certainly the largest request we get. Proper now most frameworks are a bit too freeform (not sufficient constraints) to do that reliably. That stated Svelte is one of the best candidate for that, which is actively being labored on, we name it sveltosis.
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