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v5.0.16

Omi - Next generation web framework using web components with omio fallback(IE8+) in 4kb JavaScript. Easy to MVVM.

Why Omi?

• Tiny size. (4kb gzipped)
• Excellent compatibility(IE8+) with omio
• Real MVVM with mappingjs strong support
• Supports TypeScript
• Reactive data-binding
• Enhanced CSS, rpx unit support base on 750 screen width
• Based on Shadow DOM
• Easy to debug via Omi DevTools Extension [Install from Chrome WebStore]
• Compliance with browser trend and API design
• Merge Web Components and JSX into one framework
• Built in observe feature (No need to call this.update())
• 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 and it's turing complete(template engine is not, es template string is but grammatical noise is too loud)
• The original Path Updating system. Proxy-based automatic accurate update, low power consumption, high degree of freedom, excellent performance, easy integration of requestIdleCallback
• Say goodbye to this.update method when using store system! It will automatically update UI partially when data is changed
• Look at Facebook React vs Web Components，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
• With a Store system, 99.9% of projects don't need time travel, and not only Redux can travel, please don't come up on Redux, Omi store system can meet all projects
• Scoped CSS's best solution is Shadow DOM, 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.

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

Omi	React

Omi uses Shadow DOM based style isolation and semantic structure.

Ecosystem of Omi

Project	Description
omi-docs	Omi official documents
omio	Omi for old browsers(IE8+ and mobile browsers).
md2site	Static Site Generator with markdown powered by Omio.
omi-mvvm	MVVM comes back bravely with mappingjs strong support.
omi-chart	Simple HTML5 Charts using chart-x tag.
omi-html	Using htm in omi.
omi-30-seconds	Useful Omi snippets that you can understand in 30 seconds.
omi-canvas	Perfect fusion of web components, jsx and canvas.
omi-mp	Develop and generate Web HTML5 Single-Page Applications by wechat mini program. The output source is base on omi + omi-router
omi-router	Omi official router. → DEMO
omi-devtools	Browser DevTools extension
omi-cli	Project scaffolding
omi-ex	Omi.js extension(TypeScript)
omi-transform	Omi / css3transform integration. Made css3 transform super easy in your Omi project.
omi-tap2	Native tap event support(omi v4.0.24+）
omi-tap	Support tap event in your omi project
omi-finger	Support touch and gesture events in your Omi project.
omi-touch	Smooth scrolling, rotation, pull to refresh and any motion for the web.
omi-use	React hooks like API
omi-native	Render web components to native
omi-weui	Weui for Omi by @132yse.
omi-i18n	Internationalization solution for omi.js using i18next ecosystem
omi-page	Tiny client-side router by page

Useful Resources

Title Name	Other language	Related
Developer Tools support for Web Components in Firefox 63
Develop W3C Web Components with WebAssembly
60FPS Animation In Omi	简体中文 한국어
Render Web Components To Native	简体中文 한국어
Shadow Dom In Depth	简体中文
Part Theme Explainer	求翻译
Web Components MDN	简体中文
Web Components Google
Web Components Org
Proxy MDN	简体中文 한국어
CSS Variables	简体中文 한국어
CSS Shadow Parts
Platform HTML5
Using requestIdleCallback	简体中文	A polyfill
The Power Of Web Components	简体中文
ShadowRoot	简体中文

Overview of the Readme

• Ecosystem of Omi
• Useful Resources
• omi-mp
• Add Omi in One Minute
• Add Omi in 30 Seconds
• Getting Started
  • Install
  • Project Template
  • Hello Element
  • TodoApp
  • Store
  • Mitt
  • Observe
  • Lifecycle
• Debugging
• React to Omi
• Browsers Support
• Contributors
• Maintainers
• Thanks
• License

Add Omi in One Minute

This page demonstrates using Omi with no build tooling.

• Online Demo!
• Omi.js CDN

<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8" />
  <title>Add Omi in One Minute</title>
</head>

<body>
  <script src="https://unpkg.com/omi"></script>
  <script>
    const { WeElement, h, render, define } = Omi

    define('like-button', class extends WeElement {
        install() {
          this.data = { liked: false }
        }

        render() {
          if (this.data.liked) {
            return 'You liked this.'
          }

          return h(
            'button',
            {
              onClick: () => {
                this.data.liked = true
                this.update()
              }
            },
            'Like'
          )
        }
      })

    render(h('like-button'), 'body')
  </script>
</body>

</html>

You can also use like-button tag directly in HTML：

<body>
  <like-button />
</body>

Add Omi in 30 Seconds

You can also quickly build omi projects using modern JS code:

import { render, WeElement, tag, observe } from "omi"

@observe
@tag("my-counter")
class MyCounter extends WeElement {

  data = {
    count: 0
  }

  sub = () => {
    this.data.count--
  }

  add = () => {
    this.data.count++
  }

  render() {
    return (
      <div>
        <button onClick={this.sub}>-</button>
        <span>{this.data.count}</span>
        <button onClick={this.add}>+</button>
      </div>
    )
  }
}

render(<my-counter />, "body")

→ counter demo

You will find that the MyCounter class name defined above is never used. So you can also use the following way to avoid Eslint hints:

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

define('my-counter', class extends WeElement {
    static observe = true
    
    data = {
      count: 1
    }

    sub = () => {
      this.data.count--
    }

    add = () => {
      this.data.count++
    }

    render() {
      return (
        <div>
          <button onClick={this.sub}>-</button>
          <span>{this.data.count}</span>
          <button onClick={this.add}>+</button>
        </div>
      )
    }
  })

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

You can also be defined as a form of pure functions:

import { define, render } from 'omi'

define('my-counter', function() {
  const [count, setCount] = this.use({
    data: 0,
    effect: function() {
      document.title = `The num is ${this.data}.`
    }
  })

  this.useCss(`button{ color: red; }`)

  return (
    <div>
      <button onClick={() => setCount(count - 1)}>-</button>
      <span>{count}</span>
      <button onClick={() => setCount(count + 1)}>+</button>
    </div>
  )
})

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

If you don't need effect, you can use useData directly:

const [count, setCount] = this.useData(0)

Getting Started

Install

$ npm i omi-cli -g               # install cli
$ omi init my-app     # init project, you can also exec 'omi init' in an empty folder
$ cd my-app           # please ignore this command if you executed 'omi init' in an empty folder
$ 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

About compiled website URL：

• build env doc
• build problem

Such as in windows:

"scripts": {
  "start": "node scripts/start.js",
  "_build": "node scripts/build.js",
  "build":"set PUBLIC_URL=https://fe.wxpay.oa.com/dv&& npm run _build"
}

In mac os:

"scripts": {
    "start": "node scripts/start.js",
    "_build": "node scripts/build.js",
    "build":"PUBLIC_URL=https://fe.wxpay.oa.com/dv npm run _build",
    "fix": "eslint src --fix"
  },

If you only want to use relative addresses:

"build":"set PUBLIC_URL=.&& npm run _build"  //windows
"build":"PUBLIC_URL=. npm run _build",       //mac os

Project Template

Template Type	Command	Describe
Base Template	omi init my-app	Basic omi project template.
Omio Template	omi init-o my-app	Basic omi project template for old browsers(IE8+ and mobile browsers).
Mobile Template	omi init-weui my-app	Mobile web app template with weui and omi-router.
TypeScript Template(omi-cli v3.0.5+)	omi init-ts my-app	Basic template with typescript.
SPA Template(omi-cli v3.0.10+)	omi init-spa my-app	Single page application template with omi-router.
omi-mp Template(omi-cli v3.0.13+)	omi init-mp my-app	Developing web with mini program template.
MVVM Template(omi-cli v3.0.22+)	omi init-mvvm my-app	MVVM template.

CLI's auto-created project scaffolding is based on a single-page create-react-app to be converted into a multi-page one, with configuration issues to see create-react-app user guide

Hello Element

Define a custom element by extending WeElement base class:

import { define, WeElement } from 'omi'

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

  css() {
    return `
        div {
          color: red;
          cursor: pointer;
        }`
  }

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

Using hello-element:

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

define('my-app', class extends WeElement {
  data = { abc: 'abc', passToChild: 123 }

  // define CustomEvent Handler
  onAbc = evt => {
    // get evt data by evt.detail
    this.data.abc = ' by ' + evt.detail.name
    this.data.passToChild = 1234
    this.update()
  }

  css() {
    return `
         div{
             color: green;
         }`
  }

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

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

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

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

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

"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:

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

{
  "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 of webpack, For example, the following configuration:

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

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

import { tag, WeElement render } from 'omi'

// typeof cssStr is string
import cssStr from './_index.css'

@tag('my-app')
class MyApp extends WeElement {

  css() {
    return cssStr
  }
  ...
  ...
  ...

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:

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

define('todo-list', function(props) {
  return (
    <ul>
      {props.items.map(item => (
        <li key={item.id}>{item.text}</li>
      ))}
    </ul>
  )
})

define('todo-app', class extends WeElement {
  static observe = true

  data = { items: [], text: '' }

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

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

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

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

Store

Say goodbye to this.update method when using store system! It will automatically update the UI partially when data is changed. The powerful Store architecture is high-performanced since all the data is mounted on the store, except for components that rely on props to determine the state of the component.

export default {
  data: {
    items: [],
    text: "",
    firstName: "dnt",
    lastName: "zhang",
    fullName: function() {
      return this.firstName + this.lastName;
    },
    globalPropTest: "abc", // Change it will refresh all elements without changing the components and page declaring data dependency.
    ccc: { ddd: 1 } // Change it will refresh all elements without changing the components and page declaring data dependency.
  },
  globalData: ["globalPropTest", "ccc.ddd"],
  add: function() {
    if (!this.data.text.trim().length) {
      return;
    }
    this.data.items.push({
      text: this.data.text,
      id: Date.now()
    });
    this.data.text = "";
  }
  // Default value is false, set to true will update all instances when data changing.
  // updateAll: true
};

Custom Element requires declaring dependent data so that Omi stores compute the dependency path based on the data declared on the custom component and update it locally as needed. Such as:

define('todo-app', class extends WeElement {
  // If you use store, the data is only used to declare dependencies.
  static get data() {
    return { items: [], text: "" };
  }
  // ...
  handleChange = e => {
    this.store.data.text = e.target.value;
  };

  handleSubmit = e => {
    e.preventDefault();
    this.store.add();
  };
})

• The logic of data is encapsulated in the store definition method (such as store.add).
• Views are only responsible for passing data to store, such as calling store.add or setting store.data.text on top.

You need to inject store from the root node at render time to use this store:

render(<todo-app />, "body", store);

→ Store Source Code

Summary：

• store.data is used to list all attributes and default values (except the components of the view decided by props).
• The static data of the element is used to list the attributes of the dependent store.data (Omi will record path) and update on demand.
• If there are few simple components on the page, updateAll can be set to true, and components and pages don't need to declare data, and they don't update on demand
• The path declared in globalData refreshes all pages and components by modifying the value of the corresponding path, which can be used to list all pages or most of the public properties path

Mitt

If you don't want to use store's data system, you can also use publish subscribe mode. For example, using mitt across component communication in Omi:

• cross-component-communication

Observe

Omi Observe

You can also use observe to create response views for element who no need store, such as:

import { define, WeElement } from "omi"

define("my-app", class extends WeElement {
  static observe = true

  install() {
    this.data.name = "omi"
  }

  onClick = () => {
    this.data.name = "Omi V4.0"
  }

  render(props, data) {
    return (
      <div onClick={this.onClick}>
        <h1>Welcome to {data.name}</h1>
      </div>
    )
  }
})

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
afterUpdate	after update (deprecated)
updated	after update
beforeRender	before render()
receiveProps	parent element re-render will trigger it

Debugging

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 or Vue has. It just adds a panel to the Elements' sidebar and it's powerful as much as React and Vue DevTools.

React to Omi

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

• Diff Split
• Diff Unified
• Before
• After

Browsers Support

Omio - Omi for old browsers(IE8+ and mobile browsers)

Omi 4.0+ works in the latest two versions of all major browsers: Safari 10+, IE 11+, and the evergreen Chrome, Firefox, and Edge.

→ Polyfills

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

Contributors

Maintainers

• @f
• @LeeHyungGeun
• @dntzhang
• @xcatliu

Please contact us for any questions. Also, Add Omi QQ Group.

Thanks

• preact
• JSONPatcherProxy
• create-react-app
• JSX

License

MIT © Tencent