Getting Started

What is Weex?#

Weex is a framework for building high-performance mobile applications with a modern web development experience.

Weex enables developers to use modern web development experience to build Android, iOS, and web apps with a single codebase. In practice, you can use JavaScript and modern front-end frameworks to develop mobile apps after integrating the WeexSDK.

The structure of Weex is decoupled: the render engines are separated from the syntax layer. Weex does not rely on any specific front-end framework; however, Weex mainly supports Vue.js and Rax.

Another primary goal of Weex is to keep up with modern development technologies and platform capabilities both for web and native. Productivity and performance can coexist in Weex. Writing Weex pages feels the same as writing web pages. In fact, rendering Weex pages is the same as rendering native pages.

Overview#

If you just want to try Weex, you do not need to install anything. There is an online playground for Weex wherein you can write single page examples without any installation or configuration. The source code should be written in Vue.js single file component syntax (also known as the *.vue files), and the rendered result from editor pane will be displayed in a mock phone shell.

Here is an example written in Weex and Vue.js:

Weex Example

This example renders a word “Yo” in the center of the screen. If you want to preview the rendered result on a mobile device, you need to install the Weex playground app, or integrate Weex SDK into your own app and scan your page’s QR code with your playground app or your own app (with the QR scan feature to load scanned URL with Weex SDK). Thereafter, you will see the rendered result on your device.

Within the <template> of the source code, you will notice the <div> element, which is widely used on the web, and is also the generic container in Weex. The <text> component, however, is provided by Weex and is a block-level text container.

The raw text node can only be placed in the <text> component, otherwise, it will be ignored.

Within the <style> tag, you can write CSS to describe the styles of a component, and those styles are scoped forcibly in Weex.

Native Components#

In the example above, the <div> and the <text> elements are rendered into corresponding native views on the mobile device. As such, they do not implement the HTMLElement interface.

Native Components

Weex implements render engines both on iOS and Android and provides a group of built-in components for basic usage. Based on these components, you can compose and wrap more custom components.

Although the components in Weex look like HTML tags, you are not able to use all of them, instead, you can only use the built-in components and your custom components.

Behind the scenes, Weex uses native widgets. Although Weex emphasizes consistency on each mobile platform, we still embrace the platform’s own behavior and UI differences. For example, the <switch> component may look different on Android and iOS (the appearance on the web simulates iOS).

Different switch

If you want to use additional native components, other than the built-in components provided by Weex, you need to implement them on each platform and keep their behaviors consistent. The most practical way is to integrate the existing native components to Weex platform. /_ need explanation _/

Native Modules#

For those features that do not rely on the UI, Weex wraps them into modules. You can use weex.requireModule('xxx') to require them. Weex modules provide easy access to native capabilities in JavaScript, such as network, storage, clipboard, and navigator. For example, you can use stream module to fetch the star count of Vue.js.

Similarly, Weex provides a group of built-in modules for basic usage, and supports the integration of the existing native modules into the Weex platform.

Here are some documents about how to extend native components and native modules for Weex:

Write Once, Run Everywhere#

Yes, Weex can build for Android, iOS, and Web apps from a single codebase.

Using the same source code across different platforms can dramatically increase development productivity and simplify the testing, building, and publishing processes. On this basis, Weex can combine the front-end’s packaging and testing process with the mobile’s publishing and monitoring system to improve development efficiency.

You can read How it works and Design Principles to know more about the technologies and ideas behind Weex.

Although Weex uses a single codebase, you can still write platform specific code. Weex provides weex.config.env and WXEnvironment (they are strictly equal) to get the current runtime environment. You can use WXEnvironment.platform to determine which platform the code is running on. Except for the platform, WXEnvironment contains other information pertaining to environment, such as osVersion and deviceModel. Refer to Weex variable for the complete list.

Support For Multiple Front-End Frameworks#

Front-end frameworks are the syntax layer of Weex; therefore, they are decoupled from native render engines. Weex does not bind with any specific front-end frameworks, instead, Weex brings native capabilities to the front-end.

Weex supports Vue.js and Rax as its internal front-end frameworks.

Vue and Rax

  • Vue.js is a progressive front-end framework for building user interfaces.
  • Rax is a front-end framework with React-compatible APIs.

Vue.js and Rax are already integrated into Weex SDK, you don’t need to require them manually.

However, Vue and Rax are not the only options. It is entirely possible to integrate your favorite front-end framework into Weex! There is a document Extend JS Framework that describes how to integrate a different front-end framework, the process, however, is still complicated and tricky. You need to understand many underlying details about the js-native bridge and native render engines in order to successfully integrate an alternate front-end framework.

You can read Front-End Frameworks for more details.

Create Your Own App#

The following steps assume basic knowledge of Node.js and npm. If you are not familiar with them, you can visit https://docs.npmjs.com/ to learn more about npm, and https://nodejs.org/en/docs/ to learn more about Node.js.

Weex provides a command line tool, the weex-toolkit, to help developers get start easily. The CLI can help you create a starter project, setup iOS and Android development environments, debug, install plugins, and so on.

Currently, the weex-toolkit only supports the creation of Vue.js project. The rax-cli may be helpful if you want to use Rax. Please visit Rax’s official website for more details.

Set up#

With Node.js installed, install weex-toolkit CLI globally.

npm install weex-toolkit -g

This will add the weex command to your global path, and will allow you to generate new projects with the weex create <project-name> command.
Use weex create to create a starter project:

weex create awesome-app

After doing that, a standard Weex + Vue.js project will be generated inside the awesome-app folder in the current path.

Develop#

The next step is to navigate into the generated directory, install dependencies, and start:

cd awesome-app
npm install
npm start

npm start will start a web server on port 8081. Open http://localhost:8081 in your browser of choice to see the rendered result of your Weex app. The source code is located in src/ folder. You can develop it as a normal Vue.js project.

Preview

Additionally, you can open http://localhost:8081/web/preview.html to preview the rendered result on the web in an iframe. You can also scan the QR code generated on the right using the Weex playground app to see the rendered result on the mobile device.

Build and Run#

By default, the weex create command doesn’t create the iOS and Android project, but you can use weex platform add to add them.

weex platform add ios
weex platform add android

Depending on your network environment, it may take a while to add them. Please be patient.

In order to develop the app on your local machine, you need to set up a mobile development environment. For iOS, you should install Xcode. For Android, you should install Android Studio. When the development environment is ready, run the commands below to launch your app on the simulator or the device.

weex run ios
weex run android
weex run web

Debug#

The weex-toolkit can also be used to debug your mobile apps. Just run:

weex debug

weex debug will start a debug server and open a web page in Chrome (only support V8 engine). For more technical details of weex-toolkit, please refer to the toolkit document.

Next Steps#

At this point, you should have a general understanding of Weex. The next step is to explore and try the advanced features of Weex.

If you want to use weex right now:

If you want to know the technologies and ideas behind Weex:

After getting acquainted with Weex, if you want to contribute to make it even better:

Considering that Weex is a cross-stack technology, fundamental knowledge of front-end development, Vue.js, iOS, and Android would be especially helpful.

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