import { c } from "atomico"; // 2.5kB

const MyComponent = c(
  ({name})=><host shadowDom>Hello, {name}</host>,
  {
    props: { name: String }

import { c } from "atomico"; // 2.5kB

const MyComponent = c(
  ({name})=><host shadowDom>Hello, {name}</host>,
  {
    props: { name: String }

Atomico simplifies learning, workflow and maintenance when creating webcomponents and achieves it with:

1. Scalable and reusable interfaces: with Atomico the code is simpler and you can apply practices that facilitate the reuse of your code.

2. Open communication: with Atomico you can communicate states by events, properties or methods.

3. Agnostic: your custom Element will work in any web-compatible library, eg React, Vue, Svelte or Angular.

4. Performance: Atomico has a comparative performance at Svelte levels, winning the third position in performance according to in a comparison of 55 libraries among which is React, Vue, Stencil and Lit.

API

We invite you to discover part of the development experience you will get with Atomico:

Create really fast webcomponents

Quick components to write since with Atomico you will require fewer lines of code to declare your webcomponents which will help you to be more productive

Fast in performance, since Atomico sends less code to the client, making your interface load quickly

Create web components with less code

This is thanks to a functional orientation inherited from React hooks plus some internal optimization from Atomic that ease the process of shaking the tree at compile time, achieving in this way sending the client a highly optimized JS that only has what you really use

Create webcomponents with a functional orientation

This is thanks to Atomico's reliance on React hooks syntax plus the ability to completely eliminate the need for this when using webcomponents.

Create friendly webcomponents for React, Vue and other libraries

Atomic offers additional coverage for native behavior for React and Vue, allowing your component to be more embed-friendly, example React:

First let's say that Atomico is light since it has a size close to 3kB vs React + ReactDOM that have a size close to 60kB, now if your project is already written in React I can integrate Atomico progressively since a component created can be instantiated as a component for React thanks to @atomico/react, example:

Magical 🪄, isn't it?... well now let's speed up your Atomico learning path:

How to declare a component?

Atomico, like React, allows a declaration of components using only functions, example:

From the example we will highlight the following differences:

1. In Atomico you only use one import.

2. useProp is like useState, but with the difference that useProp references the state from the webcomponent property defined in counter.props.

3. const props allows us to create the properties of our webcomponent, these are like React's propTypes, but with a big difference they are associated with the instance and can be read and modified by referencing the node, example

Now I want to invite you to learn how to declare a style using Atomico.

How do you declare styles using Atomico?

It is common to see the use of libraries such as Emotion or styled-components to encapsulate styles in React, but these add an additional cost, be it for performance or bundle, in Atomico there is no such cost.

Instances, children and slots

It is normal for React to create components that you then instantiate within other components, for example:

with Atomico there are certain differences:

1. With Atomico you can instantiate CustomElements using its constructor

The constructor in Atomic is the product of the c function and is the one you will use to register your webcomponent, example:

According to the previous example, you can instantiate MyComponent as a JSX Component, example:

This instance type allows autocompletion at the JSX level and type validation at the Typescript level.

2. With Atomico you can instantiate components as functions as long as these are only stateless functions

This will be useful for reusing templates, but always remember stateless.

Many teams decide to use Atomico for the development of their design systems thanks to its similarity with React, which greatly facilitates the incorporation of human talent into the development of design systems.

Why use Atomico to create design systems?

1. Atomico offers you Storybook 7 Support with superpowers, thanks to @atomico/storybook you can create stories without the need to declare the argTypes or args since creates them for you

2. makes it easy for you to build in NPM-friendly ESM format

3. makes it easy for you to export your code by automatically adding the metadata so that it is optimally consumed as a package, @atomico/exports can even automatically create wrappers for React, Preact and Vue

4. makes it easy for you to maintain a token system efficiently and sustainably

Use cases

IBM IX

We thank IBM IX since they have shared their experience in the development of the design system for their client Barmer, you can follow this case through Discord or Github.

Cycle as attribute:

the given value is transformed to the corresponding type, be it String, Number, Boolean, Array or Object, once transformed it is sent to the cycle as property.

Cycle as property:

evaluates if the value is of the declared type:

• If it corresponds to the type:

  1. It is saved in props.

  2. An event is emitted (if this has been configured in the prop).

  3. It is reflected as an attribute (if this has been configured in the prop).

Props is the Atomico recommended way to declare visible and accessible states at the instance level of your webcomponents, with props you can:

1. Access state via instance, example: document.querySelector("my-component").myStateProp.

2. Dispatch events on prop value change, example: document.querySelector("my-component").addEventListener("myPropChange",console.log).

3. Reflect attributes as prop, example: <my-component my-prop="...."> to document.querySelector("my-component").myProp.

4. define strict input types for props.

Syntax

Any function that represents the webcomponent will be able to associate the static object props for the declaration of reactive properties and attributes, for example:

Consider that:

1. The prop names in Camel Case format will be translated to for use as an attribute to the Kebab Case format, this behavior can be modified through the "attr" property when using a structured declaration.

2. Structured declarations require the "type" property minimally.

3. Not all types can use the "reflect" properties.

4. The declaration of the "value" property can vary depending on the type.

Simple statements

Simple statements allow setting just type validations.

Structured declaration

Improve the definition by adding utility declarations, allowing for example to reflect the property's value as attributes, automatically emit events or associate default values. Remember these types of declarations minimally require the use of the type property.

Prop.type

Prop.reflect

If the "reflect" property is set to true, its value is reflected as an attribute of the webcomponent, this is useful for the declaration of CSS states, example:

Prop.event

It allows dispatching an automatic event before the prop value change, example:

Where:

• event.type: String - optional, name of the event to be emitted when the prop is changed

• event.bubbles: Boolean - optional, indicates that the event can be listened to by containers.

• event.detail: Any - optional, allows to attach a custom detail for the event

The special properties of the event are the well-known Event Init, you can know more details in the .

Prop.value

Atomico allows the definition of default values of the props.

The association of callback as value allows generating unique values for each instance of the webcomponent, this is useful with the Object and Array types since it eliminates the references between instances.

Reactivity in the scope of the webcomponent

Atomico removes the use of "this" given its functional approach, but adds the hook [useProp] (hooks / useprop.md) which allows to reference a prop for use with a functional syntax, eg:

Recommended articles

Creating sites with Atomico is really easy and SEO friendly because:

1. With Atomico you can perform SSR and SSG thanks to tools like Astro build, with Astro + Atomico you can send previously rendered components to the client, thus giving a result at the HTML level that is really friendly with search engines.

2. Atomico being really small (3kB) your sites will load fast, especially if you only apply SSG with Atomico.

3. Atomico not only supports SSR through Astro, you can SSR today with Atomico in Next.js, Express or any environment that supports ESM modules.

4. (Coming soon) Yes, with Atomico soon you will be able to create blocks for Gutenberg easily

We recommend for SSR or SSG based sites

we recommend you for new projects

We recommend the use of build with the @atomico/astro plugin, with this you can create sites like

we recommend you for projects based on React

Preferably we recommend + React + Atomico, but in case your project inherits the use of Next.js you can do SSR with Atomico in Next.js using .

Syntax

JSX

Atomico supports jsx-runtime, alternatively you can import the h function to declare manual of the JSX pragma, eg:

Return rule

An important rule of Atomico's virtualDOM is that every webcomponent must return the <host/> tag since it represents the state of the webcomponent's DOM, such as:

1. Enable the use of the shadowDOM by declaring the shadowDom property.

2. Association of events, attributes or properties.

3. Template of the webcomponent.

Template

Event Association

Atomico considers that a property must be associated as an event if it is of the function type and begins with the prefix 'on', eg:

Simple lists

Lists with keys

the key property can receive values of the type of any type that allows generating a reference to the node, eg:

Node references

A technique inherited from React, it allows obtaining the reference of the node to which the Ref object is associated through the ref property, example:

The references must be immutable objects, to create it there is the hook that creates a reference for each instance of the webcomponent.

shadowDom property

This property allows you to declare the use of the shadowDom, eg:

Method association

You can declare a method by declaring a function in the host tag without using the prefix on in its name, eg:

If when creating or updating the DOM it does not detect the use of the property, it will be associated as a method of this, thus allowing it to be accessed from the DOM, eg:

To access the DOM safely wait for the resolution of the updated property created by the .

Syntax

const ref = useRef(optionalCurrent);

Example

import { useRef, useEffect, useState } from "atomico";

function component() {
  const ref = useRef();
  const [message, setMessage] = useState();
  useEffect(() => {
    const { current } = ref;
    current.addEventListener("input", () => {
      if (current.validity.typeMismatch) {
        setMessage("Invalid!");
      }
      current.setCustomValidity("");
    });
  }, []);
  return (
    <host>
      <input type="email" ref={ref} />
      {message && <h1>{message}</h1>}
    </host>
  );
}

Observation

The reference object is useful for referencing nodes between customHooks.

useProp allows you to work with a prop(property) of the webcomponent in a similar way to useState.

Syntax

Where :

• value: Current value of the prop.

• setValue: Callback to update the value of the prop.

• myProp: string, defines the name of the prop to be used by the hook.

Example

Where:

1. useCounter is a customHook and that it can work with any property of the webcomponent of type Number.

2. useCounter returns 2 methods increment and decrement that modify the value of the prop.

3. useCounter can be instantiated multiple times for different properties.

Special properties

render

By default, the render is configured to be used within the webcomponent by reading the return of the function, but it can be used outside of Atomico, example:

Constructor with custom element

This technique allows you to use any registered custom element without the need to know its tag-name for its use, example:

Advantage :

1. Remove leverage from tag-name

2. Infer the types of the props and autocomplete only if you use JSX and Atomico.

Constructor with DOM

Atomico allows the use of the DOM, for this it establishes its created or recovered node as a constructor, example:

Dynamic constructor

Atomico associates the variable associated with the instance as a constructor, example:

staticNode

allows to declare a node within the scope of the function as static, this will optimize the diff process between render, achieving better performance in cases of high stress of the UI, example:

the biggest advantage of this is that the node accesses the scope of the webcomponent

cloneNode

Allows to clone a node from the virtualDOM, example:

The objective of this feature is to retrieve slot and use it as a template from the webcomponent.

SSR hydration

Atomico allows reusing existing DOM in the document. This is done during the webcomponent instatiation, by setting a special property in the tag to mark it for hydration.

This can be done for shadowDom too:

Thanks for being here and getting started with Atomico. Let's talk a little about what Atomico offers today:

1. Development agility, Atomico's functional approach simplifies code at all stages of development.

2. Lightweight inside and out, Atomico allows you to create a component with less code and with a low dependency impact. Approximately 3kb.

3. Really fast, Atomico has a in the browser and an agile development experience. Let's understand what a webcomponent created with Atomico looks like:

Let's analyze the code in parts ...

1.0 Imports

What have we imported?

1. c: Function that transforms the functional component into a standard customElement.

2. css: Function that allows creating the CSSStyleSheet (CSS) for our component as long as it declares the shadowDom.

2.0 Creating Our Web Component: Custom Element Definition

2.1 Defining Component Render Function

Our function receives all the props (Properties and Attributes) declared in props, the component function declares all the logic and template of the webcomponent. An important rule within Atomico is "📌 every component created with Atomico must always return the tag".

2.2 Defining Component Properties(props) and Attributes

Atomico detects the prop (Properties and Attributes) of the component thanks to the association of the props object, this through the use of index and value allows you to define:

1. index: Name of the property and attribute.

2. value: type of the prop.

From the example we can infer that Atomico will create in our webcomponent a property and attribute called message and this can only receive values of the String type.

2.3 Defining Encapsulated Styles for the Component

Atomico detects the static styles of your component thanks to the association of the styles property:

styles accepts individual or list CSSStyleSheet (CSS) values, the return from the css function is a standard CSSStyleSheet, so it can be shared outside of Atomico.

Web Component Registration and Definition

To create our standard customElement we will have to deliver our functional component to the c function of the Atomico module, the c function will generate as a return a customElement that can be defined or extended.

Example

Syntax

const refHost = useHost();

Returns the instance of the webcomponent in reference format, this reference allows to extend behaviors when creating customHooks.

Example

import { useHost, useEffect } from "atomico";

function useListener(type: string, callback: (ev: Event) => void) {
  const ref = useHost();
  useEffect(() => {
    const { current } = ref;
    current.addEventListener(type, callback);
    return () => current.removeEventListener(type, callback);
  }, []);
}

From the example we can highlight that useListener is a customHook that allows listening to an event from the webcomponent without the need to link said event to the VirtualDOM.

It is normal that the state of your component depends on the references of a slot, this hook facilitates the process of observing these references without the need to associate the changes to a state.

Syntax

const update = useUpdate();

Where:

1. update: Callback, force component update.

Hooks only for webcomponents

Hooks homogolates of React

@atomico/hooks

Atomico today offers more Hooks external to the core, we invite you to visit with more than 50 hooks to enhance the use of webcomponents 😎

Syntax

useEffect(effectCallback, optionalArgumentList);

Where :

1. effectCallback : Function that is executed one or more times according to optionalArgumentList,effectCallback can return a function that will be executed only if effectCallback is executed again or the webcomponent is unmounted.

2. optionalArgumentList: Array of arguments that controls the execution of effectCallback, if an argument ofoptionalArgumentList changes it will trigger that effectCallback is executed again without first cleaning the effects subscribed by the previous execution.

Example

useLayoutEffect

useLayoutEffect replicates the logic of useEffect but with synchronous execution after rendering.

useInsertionEffect

useLayoutEffect replicates the logic of useEffect but with synchronous execution before rendering.

Syntax

const [state, setState] = useState(optionalInitialState);

Where:

1. const [state,setState] : Return of useState, the arguments allow reading and updating of the state associated with the hook instance.

   • state : Current state.

   • setState: Current status updater.

2. useState( optionalInitialState ): Function that associates the state to the webcomponent:

   • optionalInitialState: Optional parameter that defines the initial state associated to the hook instance, If optionalInitialState is a function it will be executed in order to obtain the initial state only at the moment of the hook instance for the first time.

Example

Syntax

Where:

• dispatchEvent: callback, dispatches the event from the webcomponent and allows defining the detail by receiving a first parameter

• myEvent: string, name of the event to dispatch.

• eventInit: optional object, event configuration.

Examples

Event customization

The second parameter of useEvent allows customizing the behavior of the even:

Recommended articles

This hook enables you to take control of the context from the component that instantiates useProvider, thus avoiding the need to instantiate the context node in the DOM.

Example of the useProvider hook:

import { createContext, useProvider, c } from "atomico";

export const Theme = createContext({
    color: "white",
    background: "black"
});

export const App = c(()=>{
    useProvider(Theme,{
        color: "red",
        background: "yellow"
    });
    
    return <host shadowDom><slot/></host>
});

Objective

Avoid creating an instantiable context node in the DOM.

useId is a Atomico Hook for generating unique IDs that can be passed to accessibility attributes.

Syntax

import { useId } from "atomico";

const stringId = useId();

Example

Use ID generate a unique ID for each component, this id can be useful for referencing CSS selectors or creating names for inputs that only the component knows about.

With the new contexts API you will be able to easily communicate components without the need to handle events, by default the communication is top down, but through it you can share anything as long as it is defined as an object.

Atomico's api is similar to React's Context api, let's explore the behavior of Atomico's context api:

createContext

create a custom Element as a context, this will serve to synchronize all the components nested within it, you must always remember to declare the tagname of this customElement, example

useContext

It allows to consume the return of createContext, let's go back to the previous example and suppose that we want to consume the customElement Theme created by createContext, the code for this would be the following:

In this way useContext captures the value of the parent component or reuses the value given by default to createContext.

Custom context values

By setting the value prop on the context, you can pass custom values down the sub-tree:

When to use the Context API?

It is ideal to always prioritize a conversation between parent and child through events or props api, but sometimes the depth of the DOM makes this process difficult, for this the context api has been introduced. To remove DOM depth limitations and ensure synchronization based on a unique identifier, some ideal cases to solve with the context api are:

1. Synchronize states or private methods between components.

2. Share a value or states inherited from the parent regardless of DOM depth.

We recommend the @web/test-runner tool, if your project was created with the command npm init @atomico the test environment will be preconfigured, you can see this pre-configuration at https://github.com/atomicojs/base/tree/2-started.

Advanced (Documentation in progress)

To scale the test environment you can complement with tools such as:

1. : allows you to automate interactions and evaluate interactions of your interface.

2. : Allows you to evaluate the appearance changes of your component or application between versions.

useAsync

with a similar approach to React's use hook, but with scope approach.

scope approach? yes, this hook seeks to resolve a promise from a callback return, this allows you to regenerate the promise according to the scope, example:

import { useAsync } from "atomico";

const getUser = (userId) => fetch(`users/${userId}`).then((res) => res.json());

function component

import { Props, useAsync } from "atomico";

const getUser = (userId: number): Promise<{ name: string }> =>
  fetch(`users/${userId}

where:

• getUser: async callback.

• [ userId ]: arguments that if changed regenerate the promise.

• user : promise return

Like useEffect, the promise will be executed every time the arguments to the second parameter of useAsync change.

useSuspense

allows to listen to all useAsync executions nested in the component, example:

Syntax

const memoValue = useMemo(callback, optionalArgumentList);

Where :

1. memoValue : Return memorized by useMemo.

2. callback: Function that is executed one or more times according to optionalArgumentList.

3. optionalArgumentList: Array of arguments that controls the execution of callback, if an argument of optionalArgumentList changes it will trigger that callback is executed again.

useCallback

Hook that allows you to memorize a callback so that it keeps its scope

Where:

1. memoCallback : Return memorized by useCallback.

The idea is to create an instance of AbortController every time the hook's parameters change. Each parameter change will abort the previously generated controller, thus cancelling any subscribed promises.

Example

The significant advantage of using useAbortController is the automatic cancellation of asynchronous processes that depend on it when modifying the arguments provided to useAbortController (similar to useEffect).

The purpose of this hook is to facilitate the consumption of promises.

Syntax

where:

• callback : asynchronous function.