omi/README.md

English | [简体中文](./README.CN.md) 

<p align="center"><img src="https://tencent.github.io/omi/assets/omi-logo2019.svg" alt="omi" width="100"/></p>
<p align="center"><img src="https://tencent.github.io/omi/assets/omi.jpg" alt="omi" width="1000"/></p>
<h2 align="center">Omi -  Front End Cross-Frameworks Framework</h2>
<p align="center">Merge Web Components, JSX, HTM, Virtual DOM, Functional style and Proxy into one framework with tiny size and high performance. Write components once, using in everywhere, such as Omi, React, Preact, Vue or Angular.</p>

## Quick Preview

Pass data through the component tree without having to pass props down manually at every level by store, auto update the view on demand.

```jsx
import { define, render } from 'omi'

class Store {
  data = {
    count: 1
  }
  sub = () => {
    this.data.count--
  }
  add = () => {
    this.data.count++
  }
}

define('my-counter', _ => (
  <div>
    <button onClick={_.store.sub}>-</button>
    <span>{_.store.data.count}</span>
    <button onClick={_.store.add}>+</button>
  </div>
), {
    use: ['count'], 
    //or using useSelf, useSelf will update self only, exclude children components
    //useSelf: ['count'], 
    css: `span { color: red; }`,
    installed() {
      console.log('installed')
    }
  })

render(<my-counter />, 'body', new Store)
```

* `<my-counter></my-counter>` can be used in any framework or no framework, such as `document.createElement('my-counter')`

You can also implement computed props through use, such as:

```jsx
define('my-counter', _ => (
  <div>
    <button onClick={_.store.sub}>-</button>
    <span>{_.store.data.count}</span>
    <button onClick={_.store.add}>+</button>
    <div>Double: {_.using.doubleCount}</div>
  </div>
), {
    use: [
      'count',
      {
        doubleCount: [
          'count',
          count => count * 2
        ]
      }]
  })
```

You can also use `useSelf`, `useSelf` only updates itself. When using `useSelf`, the corresponding attributes are accessed through. `usingSelf` in JSX.

Path is also supported:

```js
class Store {
  data = {
    list: [
      { name: { first: 'dnt', last: 'zhang' } }
    ]
  }
}

...
...

define('my-counter', _ => (
  ...
  ...
), {
    use: [
      'list[0].name', //Direct string, accessible through this.using[0] 
      {
        //alias，accessible through this.using.fullName
        fullName: [
          ['list[0].name.first', 'list[0].name.last'],
          (first, last) => first + last
        ]
      }]
  })
```

![](https://github.com/Tencent/omi/raw/master/assets/store.jpg)

### API and Hooks

```jsx
define('my-component', _ => (
  ...
  ...
), {
    use: ['path', 'path.a', 'path[1].b'],
    useSelf: ['path.c', 'path[1].d'],
    css: 'h1 { color: red; }',
    propTypes: {

    },
    defaultProps: {

    },

    //life cycle
    install() { }, 
    installed() { }, 
    uninstall() { }, 
    receiveProps() { },
    beforeUpdate() { }, 
    updated() { }, 
    beforeRender() { }, 
    rendered() { } 

  })
```

## Ecosystem of Omi

#### Base

| **Project**                         | **Description**                           |
| ------------------------------- | ----------------------------------- |
| [omi-docs](https://tencent.github.io/omi/site/docs/index.html) and [codepen](https://codepen.io/collection/DrMYgV/) and [webcomponents.dev](https://webcomponents.dev/)| Omi official documents |
| [omim![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png)](https://github.com/Tencent/omi/tree/master/packages/omim)| Cross **frameworks** and **themes** components.([DOCS & REPL](https://tencent.github.io/omi/packages/omim/docs/build/index.html) && [JOIN US!](https://github.com/Tencent/omi/tree/master/packages/omim#contribution))|
| [omi-kbone![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png) ](https://github.com/Tencent/omi/tree/master/packages/omi-kbone)| 使用 omi + [kbone](https://github.com/wechat-miniprogram/kbone) 多端开发(小程序和Web)的贪吃蛇游戏。 |
| [omio](https://github.com/Tencent/omi/tree/master/packages/omio)| Omi for old browsers with same api(IE8+)|
| [omis![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png) ](https://github.com/Tencent/omi/tree/master/packages/omis)| Omis + React|
| [omiv![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png) ](https://github.com/Tencent/omi/tree/master/packages/omiv)| Omiv + Vue|
| [omi-ssr](https://github.com/Tencent/omi/tree/master/packages/omi-ssr)| Server-side rendering(support omio only)|
| [omi-router](https://github.com/Tencent/omi/tree/master/packages/omi-router) |Omi official router in 1KB js|
| [omi-cli](https://github.com/Tencent/omi/tree/master/packages/omi-cli)| Project scaffolding. [→ Base Templates](https://github.com/Tencent/omi/tree/master/packages/omi-cli/template) and [→ Other Templates](https://github.com/omijs) |
| [omi-devtools](https://github.com/f/omi-devtools)| Browser DevTools extension |
| [omiu](https://tencent.github.io/omi/packages/omiu/examples/build/index.html)| Simple Omi UI |
| [omil](https://github.com/Wscats/omil)|Webpack loader for Omi.js components.([DOCS](https://wscats.github.io/omi-docs/public/home/))|
| [omi-snippets](https://github.com/Wscats/omi-snippets) |A beautify VSCode extension for .omi or .eno file, [Install now!](https://marketplace.visualstudio.com/items?itemName=Wscats.omi-snippets)|
| [obaa](https://github.com/Tencent/omi/tree/master/packages/obaa) or [JSONPatcherProxy](https://github.com/Palindrom/JSONPatcherProxy) | Observe or Proxy any object's any change |

#### Snake MVP

| **Project**                         | **Description**                           |
| ------------------------------- | ----------------------------------- |
| [omi-snake![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png) ](https://github.com/Tencent/omi/tree/master/packages/omi-snake) & [→ Touch the demo](https://tencent.github.io/omi/packages/omi-snake/build/index.html)| The Snake-Eating Game Based on MVP Architecture Written by Omi |
| [omi-kbone-snake![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png) ](https://github.com/Tencent/omi/tree/master/packages/omi-kbone)| omi-kbone 写的 MVP 架构的贪吃蛇小程序 |
| [Preact-snake![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png)](https://github.com/Tencent/omi/tree/master/packages/preact-css/examples/snake) & [→ Touch the demo](https://tencent.github.io/omi/packages/preact-css/examples/snake/build/)| The Snake-Eating Game Based on MVP Architecture Written by Preact + Preact-CSS + Omis |
| [[P]react-snake![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png)](https://github.com/Tencent/omi/tree/master/packages/react-snake) & [→ Touch the demo](https://tencent.github.io/omi/packages/react-snake/build/index.html)| The Snake-Eating Game Based on MVP Architecture Written by React/Preact |

#### Mini Program(小程序)

| **Project**                         | **Description**                           |
| ------------------------------- | ----------------------------------- |
| [react-kbone![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png) ](https://github.com/Tencent/omi/tree/master/packages/react-kbone)| 直接使用 React 开发小程序或 Web，基于 [kbone](https://github.com/wechat-miniprogram/kbone) |
| [preact-kbone![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png) ](https://github.com/Tencent/omi/tree/master/packages/preact-kbone)| 直接使用 Preact 开发小程序或 Web，基于 [kbone](https://github.com/wechat-miniprogram/kbone) |
| [omix![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png)](https://github.com/Tencent/omi/tree/master/packages/omix)| 极小却精巧的小程序框架|
| [omi-cloud](https://github.com/Tencent/omi/tree/master/packages/omi-cloud)| 小程序•云开发|
| [omip](https://github.com/Tencent/omi/tree/master/packages/omip)| 直接使用 Omi 开发小程序或 H5 SPA|
| [mps](https://github.com/Tencent/omi/tree/master/packages/mps)| 原生小程序增强框架(JSX + Less 输出 WXML + WXSS)，也支持 QQ 轻应用 |
| [cax](https://github.com/Tencent/omi/tree/master/packages/cax)| 小程序 Canvas 和 SVG 渲染引擎 |
| [omi-mp](https://github.com/Tencent/omi/tree/master/packages/omi-mp)| 通过微信小程序开发和生成 Web 单页应用(H5 SPA)|
| [westore](https://github.com/Tencent/westore/)| 小程序状态管理 |
| [comi](https://github.com/Tencent/omi/tree/master/packages/comi)| 小程序代码高亮和 markdown 渲染组件 |
| [wx-touch-event](https://github.com/qbright/wx-touch-event)| 基于 [AlloyFinger](https://github.com/AlloyTeam/AlloyFinger) 改造的小程序手势解决方案 |

#### Other

| **Project**                         | **Description**                           |
| ------------------------------- | ----------------------------------- |
| [omi-piano![](https://raw.githubusercontent.com/dntzhang/cax/master/asset/hot.png)](https://github.com/Wscats/piano) |Build piano with Omi and Omi Snippets, [Enjoy now!](https://wscats.github.io/piano/build/)|
| [omi-chart](https://github.com/Tencent/omi/tree/master/packages/omi-chart)| Simple HTML5 Charts using chart-x tag.|
| [md2site](https://tencent.github.io/omi/assets/md2site/)| Static Site Generator with markdown powered by Omio.|
| [omi-30-seconds](https://github.com/Tencent/omi/tree/master/packages/omi-30-seconds)| Useful Omi snippets that you can understand in 30 seconds.|
| [omi-canvas](https://github.com/Tencent/omi/tree/master/packages/omi-canvas)| Perfect fusion of web components, jsx and canvas.|
| [omi-swiper](https://github.com/loo41/Omi-Swiper)| Omi + Swiper  |
| [omi-vscode](https://github.com/ZainChen/omi-vscode)| VSCode extension for omi, [Install now!](https://marketplace.visualstudio.com/items?itemName=ZainChen.omi) |
| [omi-ex](https://github.com/Tencent/omi/tree/master/packages/omi-ex)| Omi.js extension(TypeScript) |
| [omi-transform](https://github.com/Tencent/omi/tree/master/packages/omi-transform)|Omi / [css3transform](https://tencent.github.io/omi/packages/omi-transform/css3transform/) integration. Made css3 transform super easy in your Omi project.|
| [omi-finger](https://github.com/Tencent/omi/tree/master/packages/omi-finger)|Support touch and gesture events in your Omi project.|
| [omi-touch](https://github.com/Tencent/omi/tree/master/packages/omi-touch)|Smooth scrolling, rotation, pull to refresh and any motion for the web.|
| [omi-native](https://github.com/Tencent/omi/tree/master/packages/omi-native)|Render web components to native|
| [omi-i18n](https://github.com/i18next/omi-i18n)| Internationalization solution for omi.js using i18next ecosystem |
| [omi-page](https://github.com/Tencent/omi/tree/master/packages/omi-page) |Tiny client-side router by [page](https://github.com/visionmedia/page.js)|
| [omie](https://github.com/Wscats/omi-electron) |Build cross platform desktop apps with Omi.js and Electron.js|
| [omi-cv](https://github.com/Wscats/CV) |Create a front-end engineer curriculum vitae, [Get Started!](http://wscats.github.io/CV/omi/build/index.html)|

## Why Omi?

- Tiny size and [High performance](https://tencent.github.io/omi/packages/omi/examples/perfs/)
- Cross frameworks(react, preact, vue, angular), components of omi are pure custom elements
- One framework. Mobile & desktop & mini program
- Stateless View Architecture Design
- Be friendly to custom elements, you can pass `false` attributes to elements through string `'0'` or string `'flase'`, you can [pass `object` attributes to elements through `:` prefix and `Omi.$`](https://github.com/Tencent/omi/releases/tag/v6.8.0)
- [Easy two way binding by extend api](https://codepen.io/omijs/pen/aeLYjx)
- Supports TypeScript
- Reactive data-binding
- [Native tap event support](https://github.com/Tencent/omi/releases/tag/v4.0.24)
- Having Cross-frameworks UI components - [omim](https://tencent.github.io/omi/packages/omim/docs/build/index.html)
- Excellent compatibility(IE8+) with [omio](https://github.com/Tencent/omi/tree/master/packages/omio)
- Enhanced CSS, [rpx unit support](https://github.com/Tencent/omi/releases/tag/v4.0.26) base on **750** screen width
- Compliance with browser trend and API design
- Merge [**Web Components**](https://developers.google.com/web/fundamentals/web-components/), [**JSX**](https://reactjs.org/docs/introducing-jsx.html) and [**HTM**](https://github.com/developit/htm) into one framework
- Web Components can also be a data-driven view, **`UI = fn(data)`**.
- JSX is the best development experience (code intelligent completion and tip) UI Expression with least [grammatical noise](https://github.com/facebook/jsx#why-not-template-literals) and it's turing complete(template engine is not, es template string is but grammatical noise is too loud)
- Look at [Facebook React vs Web Components](https://softwareengineering.stackexchange.com/questions/225400/pros-and-cons-of-facebooks-react-vs-web-components-polymer)，Omi **combines their advantages** and gives developers the **freedom to choose the way they like**
- **Shadow DOM merges with Virtual DOM**, Omi uses both virtual DOM and real Shadow DOM to make view updates more accurate and faster
- **Scoped CSS**'s best solution is [**Shadow DOM**](https://developers.google.com/web/fundamentals/web-components/shadowdom), the community churning out frameworks and libraries for Scoped CSS (using JS or JSON writing styles such as Radium, jsxstyle, react-style; binding to webpack using generated unique `className` `filename-classname-hash`, such as CSS Modules, Vue), are hack technologies; _and Shadow DOM Style is the perfect solution_.
- The original **Path Updating** **store system**. Proxy-based automatic **accurate** update, **low power consumption**, high degree of freedom, excellent performance, easy integration of `requestIdleCallback`,It will automatically update UI partially when data is changed

Compare TodoApp by Omi and React, Omi and React rendering DOM structure:

| **Omi**                         | **React**                           | **Omio**                           |
| ------------------------------- | ----------------------------------- |----------------------------------- |
| ![Omi](https://tencent.github.io/omi/assets/omi-render.jpg) | ![React](https://tencent.github.io/omi/assets/react-render.jpg) | ![Omio](https://tencent.github.io/omi/assets/omio.png) |

Omi uses Shadow DOM based style isolation and semantic structure.

## Useful Resources

| **Title Name**  | **Other language** | **Related**|
| ----------------------------------------- | ------------------ |-----------------|
|[Snake-Eating Game Making with Web Components of Omi and MVP Architecture](https://github.com/Tencent/omi/blob/master/tutorial/omi-web-components-snake-game-mvp.md)|||
|[Constructable Stylesheets: seamless reusable styles](https://developers.google.com/web/updates/2019/02/constructable-stylesheets)|||
|[Web Components specifications](https://github.com/w3c/webcomponents)|||
|[Web Components in a Nutshell](https://levelup.gitconnected.com/web-components-in-a-nutshell-1e114aa971b9)|||
|[Using Web Components with React in 2019](https://www.grapecity.com/blogs/using-web-components-with-react-2019)|||
|[Using Web Components in React](https://coryrylan.com/blog/using-web-components-in-react)|||
|[Styling We Components Using A Shared Style Sheet](https://www.smashingmagazine.com/2016/12/styling-web-components-using-a-shared-style-sheet/)|
|[Developer Tools support for Web Components in Firefox 63](https://blog.nightly.mozilla.org/2018/09/06/developer-tools-support-for-web-components-in-firefox-63/)||
|[Develop W3C Web Components with WebAssembly](https://medium.com/coinmonks/develop-w3c-web-components-with-webassembly-d65938284255)||
| [60FPS Animation In Omi](https://github.com/Tencent/omi/blob/master/tutorial/omi-transform.md)| [简体中文](https://github.com/Tencent/omi/blob/master/tutorial/omi-transform.cn.md) [한국어](https://github.com/Tencent/omi/blob/master/tutorial/omi-transform.kr.md)|
| [Render Web Components To Native](https://github.com/Tencent/omi/blob/master/tutorial/render-web-components-to-native.md)|[简体中文](https://github.com/Tencent/omi/blob/master/tutorial/render-web-components-to-native.cn.md) [한국어](https://github.com/Tencent/omi/blob/master/tutorial/render-web-components-to-native.kr.md)|
| [Shadow Dom In Depth](https://github.com/praveenpuglia/shadow-dom-in-depth)|  [简体中文](https://github.com/Tencent/omi/blob/master/tutorial/shadow-dom-in-depth.cn.md)|
|  [Part Theme Explainer](https://meowni.ca/posts/part-theme-explainer/)|求翻译|
|  [Web Components MDN](https://developer.mozilla.org/en-US/docs/Web/Web_Components)| [简体中文](https://developer.mozilla.org/zh-CN/docs/Web/Web_Components)|
|  [Web Components Google](https://developers.google.com/web/fundamentals/web-components/)|
|  [Web Components Org](https://www.webcomponents.org/introduction)|
|  [Web Components: the Right Way](https://github.com/mateusortiz/webcomponents-the-right-way)|
|  [Proxy MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy)|[简体中文](https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Proxy) [한국어](https://developer.mozilla.org/ko/docs/Web/JavaScript/Reference/Global_Objects/Proxy)|
|  [CSS Variables](https://developer.mozilla.org/en-US/docs/Web/CSS/Using_CSS_variables)|[简体中文](https://developer.mozilla.org/zh-CN/docs/Web/CSS/Using_CSS_variables) [한국어](https://developer.mozilla.org/ko-KR/docs/Web/CSS/Using_CSS_variables)|
|  [CSS Shadow Parts](https://drafts.csswg.org/css-shadow-parts-1/)|
|  [Platform HTML5](https://platform.html5.org/)|
| [Using requestIdleCallback](https://developers.google.com/web/updates/2015/08/using-requestidlecallback)|[简体中文](https://div.io/topic/1370)| [A polyfill](https://gist.github.com/paullewis/55efe5d6f05434a96c36)|
| [The Power Of Web Components](https://hacks.mozilla.org/2018/11/the-power-of-web-components/)|[简体中文](https://github.com/Tencent/omi/blob/master/tutorial/the-power-of-web-components.cn.md)|
|[ShadowRoot](https://developer.mozilla.org/en-US/docs/Web/API/ShadowRoot)|[简体中文](https://developer.mozilla.org/zh-CN/docs/Web/API/ShadowRoot)||

# Overview of the Readme

- [Ecosystem of Omi](#ecosystem-of-omi)
- [Useful Resources](#useful-resources)
- [Add Omi in One Minute](#add-omi-in-one-minute)
- [Getting Started](#getting-started)
  - [Install](#install)
  - [Project Template](#project-template)
  - [Hello Element](#hello-element)
  - [TypeScript Auto Complete](#typescript-auto-complete)
  - [Lifecycle](#lifecycle)
- [Debugging](#debugging)
- [Browsers Support](#browsers-support)
- [Contributors](#contributors)
- [Maintainers](#maintainers)
- [Thanks](#thanks)
- [License](#license)

## Add Omi in One Minute

This page demonstrates using Omi **with no build tooling**,  directly run in the browser.

- [→ Online Demo!](https://codepen.io/omijs/pen/PMZWNb)

```html
<!DOCTYPE html>
<html>

<head>
  <title>Omi demo without transpiler</title>
</head>

<body>
  <script src="https://tencent.github.io/omi/packages/omi/dist/omi.js"></script>
  <script>
    const { define, render, html } = Omi

    class Store {
      data = {
        count: 1
      }
      sub = () => {
        this.data.count--
      }
      add = () => {
        this.data.count++
      }
    }

    define('my-counter', _ => html`
      <div>
        <button onClick=${_.store.sub}>-</button>
        <span>${_.store.data.count}</span>
        <button onClick=${_.store.add}>+</button>
      </div>
    `, {
      use: ['count'],
      //or using useSelf, useSelf will update self only, exclude children components
      //useSelf: ['count'], 
      css: `span { color: red; }`,
      installed() {
        console.log('installed')
      }
    })

    render(html`<my-counter />`, 'body', new Store)
  </script>
</body>

</html>
```

Omi Store provides a way to pass data through the component tree without having to pass props down manually at every level, injected from the root component and shared across all subcomponents. It's very simple to use:

You can also use `my-counter` tag directly in HTML：

```jsx
<body>
  <my-counter></my-counter>
</body>
```


## Getting Started

### Install

```bash
$ npm i omi-cli -g    # install cli
$ omi init my-app     # init project
$ cd my-app           
$ npm start           # develop
$ npm run build       # release
```

> `npx omi-cli init my-app` is also supported(npm v5.2.0+).

Directory description:

```
├─ config
├─ public
├─ scripts
├─ src
│  ├─ assets
│  ├─ elements    //Store all custom elements
│  ├─ store       //Store all this store of pages
│  ├─ admin.js    //Entry js of compiler，will build to admin.html
│  └─ index.js    //Entry js of compiler，will build to index.html
```

#### Scripts

```json
"scripts": {
    "start": "node scripts/start.js",
    "build": "PUBLIC_URL=. node scripts/build.js",
    "build-windows": "set PUBLIC_URL=.&& node scripts/build.js",
    "fix": "eslint src --fix"
}
```

You can set up the PUBLIC_URL, such as：

```json
...
"build": "PUBLIC_URL=https://fe.wxpay.oa.com/dv node scripts/build.js",
"build-windows": "set PUBLIC_URL=https://fe.wxpay.oa.com/dv&& node scripts/build.js",
...
```

#### Switch omi, omio and reomi

Add or remove the alias config in package.json to switch omi and omio：

```js
"alias": {
  "omi": "omio"
}
```
    
### Project Template

| **Template Type**|  **Command**|  **Describe**|
| ------------ |  -----------|  ----------------- |
|Base Template(v3.3.0+)|`omi init my-app`| Basic omi or omio(IE8+) project template.|
|Base Template with snapshoot|`omi init-snap my-app`| Basic omi or omio(IE8+) project template with snapshoot prerendering.|
|TypeScript Template(omi-cli v3.3.0+)|`omi init-ts my-app`|Basic template with typescript.|
|Mobile Template|`omi init-weui my-app`| Mobile web app template with weui and omi-router.|
|Kbone Template|`omi init-kbone my-app`  |Developing mini program or web using omi.|

### Hello Element

Define a custom element by extending **`WeElement`** base class:

```js
import { define, WeElement } from 'omi'

define('hello-element', class extends WeElement {
  onClick = evt => {
    // trigger CustomEvent
    this.fire('abc', { name: 'dntzhang', age: 12 })
    evt.stopPropagation()
  }

  //If you need to use <hello-element></hello-element> directly in html, you must declare propTypes
  static propTypes = {
    msg: String
  }

  static css = `
      div {
        color: red;
        cursor: pointer;
      }`

  render(props) {
    return (
      <div onClick={this.onClick}>
        Hello {props.msg}
        <div>Click Me!</div>
      </div>
    )
  }
})
```

Using `hello-element`:

```js
import { define, render, WeElement } from 'omi'
import './hello-element'

define('my-app', class extends WeElement {
  data = { abc: 'abc' }

  // define CustomEvent Handler
  onAbc = evt => {
    // get evt data by evt.detail
    this.data.abc = ' by ' + evt.detail.name
    this.update()
  }

  static css = `
      div{
          color: green;
      }`
  }

  render(props, data) {
    return (
      <div>
        Hello {data.abc}
        <hello-element
          onAbc={this.onAbc}
          msg="WeElement"
        />
      </div>
    )
  }
})

render(<my-app name="Omi v4.0" />, 'body')
```

Tell Babel to transform JSX into `Omi.h()` call:

```json
{
  "presets": ["env", "omi"]
}
```

The following two NPM packages need to be installed to support the above configuration:

```bash
"babel-preset-env": "^1.6.0",
"babel-preset-omi": "^0.1.1",
```

If you use babel7, you can also use the following packages and configuration:

```bash
npm install --save-dev @babel/preset-env
npm install --save-dev @babel/preset-react
```

```js
{
  "presets": [
    "@babel/preset-env",
    [
      "@babel/preset-react",
      {
        "pragma": "Omi.h"
      }
    ]
  ]
}
```

If you don't want to write CSS in JS, you can use [to-string-loader](https://www.npmjs.com/package/to-string-loader) of webpack,
For example, the following configuration:

```js
{
  test: /[\\|\/]_[\S]*\.css$/,
  use: [
    'to-string-loader',
    'css-loader'
  ]
}
```

If your CSS file starts with "`_`", CSS will use `to-string-loader`, such as:

``` js
import { tag, WeElement render } from 'omi'

define('my-app', class extends WeElement {

  css = require('./_index.css')
  ...
  ...
  ...
```

You can also forget the tedious configuration and use omi-cli directly, no need to configure anything.
<!-- 
### TodoApp

Here is a relatively complete example of TodoApp:

```js
import { define, render, WeElement } from 'omi'

define('todo-list', class extends WeElement {
  static propTypes = {
    items: Array
  }

  render(props) {
    return (
      <ul>
        {props.items.map(item => (
          <li key={item.id}>{item.text}</li>
        ))}
      </ul>
    )
  }
})

define('todo-app', class extends WeElement {
  items = []
  text = ''

  render() {
    return (
      <div>
        <h3>TODO</h3>
        <todo-list items={this.items} />
        <form onSubmit={this.handleSubmit}>
          <input
            id="new-todo"
            onChange={this.handleChange}
            value={this.text}
          />
          <button>Add #{this.items.length + 1}</button>
        </form>
      </div>
    )
  }

  handleChange = e => {
    this.text = e.target.value
  }

  handleSubmit = e => {
    e.preventDefault()
    if (!this.text.trim().length) {
      return
    }
    this.items.push({
      text: this.text,
      id: Date.now()
    })
    this.text = ''
    this.update()
  }
})

render(<todo-app />, 'body')
``` -->

### TypeScript Auto Complete

```jsx
import { h, WeElement, tag, classNames } from 'omi';
import * as styles from './_index.less';

interface ButtonProps {
  href?: string,
  disabled?: boolean,
  type?: 'default' | 'primary' | 'danger',
  htmltype?: 'submit' | 'button' | 'reset',
  onClick?: (e: any) => void
}

const TAG = 'o-button'

declare global {
  namespace JSX {
    interface IntrinsicElements {
      [TAG]: Omi.Props & ButtonProps
    }
  }
}

@tag(TAG)
export default class oButton extends WeElement<ButtonProps> {
...
...
...
```

<img src="./assets/ts.png" alt="omi" width="427"/>

### Lifecycle

| Lifecycle method | When it gets called                          |
| ---------------- | -------------------------------------------- |
| `install`        | before the component gets mounted to the DOM |
| `installed`      | after the component gets mounted to the DOM  |
| `uninstall`      | prior to removal from the DOM                |
| `beforeUpdate`   | before update                           |
| `updated`    | after update                             |
| `beforeRender`   | before `render()`                           |
| `receiveProps`   | parent element re-render will trigger it, `return false` will prevent update action|

## Debugging

Easy to debug via [Omi DevTools Extension](https://github.com/f/omi-devtools) [[Install from Chrome WebStore](https://chrome.google.com/webstore/detail/omijs-devtools/pjgglfliglbhpcpalbpeloghnbceocmd)], using Omi DevTools you can simply debug and manage your UI **without any configuration**. Just install and debug.

Since Omi uses Web Components and Shadow-DOM, it doesn't need to have another elements panel such as React has. It just adds a panel to the **Elements' sidebar** and it's powerful as much as React DevTools.

![Omi DevTools](https://github.com/f/omi-devtools/raw/master/omi-devtools.gif)

### View registered elements

```js
console.log(Omi.elements)
```

<!-- 
## React to Omi

For example, the below is about migration React button as weui Omi button:

![react to omi](./assets/react-to-omi.png)

* [Diff Split](https://github.com/Tencent/omi/commit/9790fadaaf20cfede80bcf9213756a83fc8c3949?diff=split)
* [Diff Unified](https://github.com/Tencent/omi/commit/9790fadaaf20cfede80bcf9213756a83fc8c3949?diff=unified)
* [Before](https://github.com/Tencent/omi/blob/c8af654f1d5865dc557c0b4b8ad524f702a69be5/packages/omi-weui/src/omi-weui/elements/button/button.js)
* [After](https://github.com/Tencent/omi/blob/9790fadaaf20cfede80bcf9213756a83fc8c3949/packages/omi-weui/src/omi-weui/elements/button/button.js) -->

## Browsers Support

> [Omio](https://github.com/Tencent/omi/tree/master/packages/omio) - Omi for old browsers(IE8+)

Omi works in the latest two versions of all major browsers: Safari 10+, IE 11+, and the evergreen Chrome, Firefox, and Edge.

![→ Browsers Support](./assets/browsers-support.png)

[→ Polyfills](https://github.com/webcomponents/webcomponentsjs)

```html
<script src="https://unpkg.com/@webcomponents/webcomponentsjs@2.0.0/webcomponents-bundle.js"></script>
```

## Contribution

Build a example:

```bash
npm start example_name
```

Build omi:

```bash
npm run build
```

Unit testing

```
npm run test
```

## Contributors

<table><tbody>
      <tr><td><a target="_blank" href="https://github.com/dntzhang"><img width="60px" src="https://avatars2.githubusercontent.com/u/7917954?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/LeeHyungGeun"><img width="60px" src="https://avatars2.githubusercontent.com/u/2471651?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/xcatliu"><img width="60px" src="https://avatars1.githubusercontent.com/u/5453359?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/1921622004"><img width="60px" src="https://avatars1.githubusercontent.com/u/19359217?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/yanceyou"><img width="60px" src="https://avatars2.githubusercontent.com/u/16320418?s=60&amp;v=4"></a></td></tr><tr><td><a target="_blank" href="https://github.com/f"><img width="60px" src="https://avatars0.githubusercontent.com/u/196477?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/pasturn"><img width="60px" src="https://avatars0.githubusercontent.com/u/6126885?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/Wscats"><img width="60px" src="https://avatars3.githubusercontent.com/u/17243165?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/akira-cn"><img width="60px" src="https://avatars0.githubusercontent.com/u/316498?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/ZainChen"><img width="60px" src="https://avatars3.githubusercontent.com/u/15615524?s=60&amp;v=4"></a></td></tr><tr><td><a target="_blank" href="https://github.com/dangxuandev"><img width="60px" src="https://avatars1.githubusercontent.com/u/5436704?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/daizhan"><img width="60px" src="https://avatars0.githubusercontent.com/u/5318547?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/132yse"><img width="60px" src="https://avatars1.githubusercontent.com/u/12951461?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/elfman"><img width="60px" src="https://avatars3.githubusercontent.com/u/948001?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/NoBey"><img width="60px" src="https://avatars3.githubusercontent.com/u/10740524?s=60&amp;v=4"></a></td></tr><tr><td><a target="_blank" href="https://github.com/hilkbahar"><img width="60px" src="https://avatars2.githubusercontent.com/u/12161006?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/eyea"><img width="60px" src="https://avatars0.githubusercontent.com/u/17020223?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/guisturdy"><img width="60px" src="https://avatars1.githubusercontent.com/u/7098619?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/KidneyFlower"><img width="60px" src="https://avatars1.githubusercontent.com/u/16027183?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/zhangsanshi"><img width="60px" src="https://avatars1.githubusercontent.com/u/3771933?s=60&amp;v=4"></a></td></tr><tr><td><a target="_blank" href="https://github.com/xland"><img width="60px" src="https://avatars0.githubusercontent.com/u/2980915?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/winstonxie"><img width="60px" src="https://avatars3.githubusercontent.com/u/16422642?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/ghostzhang"><img width="60px" src="https://avatars3.githubusercontent.com/u/194242?s=60&amp;v=4"></a></td>
      <td><a target="_blank" href="https://github.com/jayZOU"><img width="60px" src="https://avatars3.githubusercontent.com/u/8576977?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/zhengbao"><img width="60px" src="https://avatars3.githubusercontent.com/u/1736166?s=60&amp;v=4"></a></td></tr><tr><td><a target="_blank" href="https://github.com/vorshen"><img width="60px" src="https://avatars3.githubusercontent.com/u/10334783?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/akira-cn"><img width="60px" src="https://avatars3.githubusercontent.com/u/316498?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/loo41"><img width="60px" src="https://avatars3.githubusercontent.com/u/28095677?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/rainmanhhh"><img width="60px" src="https://avatars3.githubusercontent.com/u/13862623?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/nbompetsis"><img width="60px" src="https://avatars3.githubusercontent.com/u/11991105?s=60&amp;v=4"></a></td></tr><tr><td><a target="_blank" href="https://github.com/CodeFalling"><img width="60px" src="https://avatars1.githubusercontent.com/u/5436704?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/daizhan"><img width="60px" src="https://avatars0.githubusercontent.com/u/5318547?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/ritschwumm"><img width="60px" src="https://avatars2.githubusercontent.com/u/547138?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/kahwee"><img width="60px" src="https://avatars3.githubusercontent.com/u/262105?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/alanyinjs"><img width="60px" src="https://avatars3.githubusercontent.com/u/25688258?s=60&amp;v=4"></a></td></tr><tr><td><a target="_blank" href="https://github.com/electerious"><img width="60px" src="https://avatars2.githubusercontent.com/u/499088?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/nanhupatar"><img width="60px" src="https://avatars1.githubusercontent.com/u/27266016?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/ilker0"><img width="60px" src="https://avatars1.githubusercontent.com/u/23511412?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/MrGrabazu"><img width="60px" src="https://avatars2.githubusercontent.com/u/6928672?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/Tagir-A"><img width="60px" src="https://avatars2.githubusercontent.com/u/23556586?s=60&amp;v=4"></a></td></tr><tr><td><a target="_blank" href="https://github.com/mahmut-gundogdu"><img width="60px" src="https://avatars2.githubusercontent.com/u/2217899?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/howel52"><img width="60px" src="https://avatars3.githubusercontent.com/u/9854818?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/yolio2003"><img width="60px" src="https://avatars1.githubusercontent.com/u/352931?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/loo41"><img width="60px" src="https://avatars3.githubusercontent.com/u/28095677?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/nbompetsis"><img width="60px" src="https://avatars1.githubusercontent.com/u/11991105?s=60&amp;v=4"></a></td></tr><tr><td><a target="_blank" href="https://github.com/WozHuang"><img width="60px" src="https://avatars2.githubusercontent.com/u/22727100?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/web-padawan"><img width="60px" src="https://avatars2.githubusercontent.com/u/10589913?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/SuperHuangXu"><img width="60px" src="https://avatars1.githubusercontent.com/u/14816052?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/LastHeaven"><img width="60px" src="https://avatars1.githubusercontent.com/u/10590077?s=60&amp;v=4"></a></td>
      <td><a target="_blank" href="https://github.com/validalias"><img width="60px" src="https://avatars3.githubusercontent.com/u/44221844?s=60&amp;v=4"></a></td></tr><tr>
      <td><a target="_blank" href="https://github.com/FAKER-A"><img width="60px" src="https://avatars2.githubusercontent.com/u/25676164?s=60&amp;v=4"></a></td>
       <td><a target="_blank" href="https://github.com/liulinboyi"><img width="60px" src="https://avatars2.githubusercontent.com/u/41336612?s=60&amp;v=4"></a></td>
        <td><a target="_blank" href="https://github.com/hulei"><img width="60px" src="https://avatars2.githubusercontent.com/u/6905072?s=60&amp;v=4"></a></td> <td><a target="_blank" href="https://github.com/mtonhuang"><img width="60px" src="https://avatars2.githubusercontent.com/u/30364922?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/Juliiii"><img width="60px" src="https://avatars2.githubusercontent.com/u/23744602?s=60&amp;v=4"></a></td></tr><tr><td><a target="_blank" href="https://github.com/mingkang1993"><img width="60px" src="https://avatars2.githubusercontent.com/u/9126292?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/liufushihai"><img width="60px" src="https://avatars2.githubusercontent.com/u/28208916?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/supermp"><img width="60px" src="https://avatars2.githubusercontent.com/u/892475?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/LeachZhou"><img width="60px" src="https://avatars2.githubusercontent.com/u/18715564?s=60&amp;v=4"></a></td><td><a target="_blank" href="https://github.com/yiliang114"><img width="60px" src="https://avatars2.githubusercontent.com/u/11473889?s=60&amp;v=4"></a></td>
        </tr></tbody></table>

Here is the [todo list](./todo.md), welcome to contribute together.

## Design philosophy

The Omi design was driven by The Zen of Python, by Tim Peters philosophy:

* Beautiful is better than ugly.
* Explicit is better than implicit.
* Simple is better than complex.
* Complex is better than complicated.
* Flat is better than nested.
* Sparse is better than dense.
* Readability counts.
* Special cases aren't special enough to break the rules.
* Although practicality beats purity.
* Errors should never pass silently.
* Unless explicitly silenced.
* In the face of ambiguity, refuse the temptation to guess.
* There should be one—and preferably only one—obvious way to do it.
* Although that way may not be obvious at first unless you're Dutch.
* Now is better than never.
* Although never is often better than right now.[n 1]
* If the implementation is hard to explain, it's a bad idea.
* If the implementation is easy to explain, it may be a good idea.
* Namespaces are one honking great idea—let's do more of those!


## Core Maintainers

- [@Wscats](https://github.com/Wscats)
- [@f](https://github.com/f)
- [@LeeHyungGeun](https://github.com/LeeHyungGeun)
- [@dntzhang](https://github.com/dntzhang)
- [@xcatliu](https://github.com/xcatliu)

Please contact us for any questions. 

## Thanks

* [preact](https://github.com/developit/preact)
* [htm](https://github.com/developit/htm) 
* [create-react-app](https://github.com/facebook/create-react-app)
* [JSX](https://github.com/facebook/jsx)
* [JSONPatcherProxy](https://github.com/Palindrom/JSONPatcherProxy)

## License

MIT © Tencent