Hi! I'm really excited that you are interested in contributing to Vue.js. Before submitting your contribution, please make sure to take a moment and read through the following guidelines:
- The `master` branch is just a snapshot of the latest stable release. All development should be done in dedicated branches. **Do not submit PRs against the `master` branch.**
- If you are resolving a special issue, add `(fix #xxxx[,#xxxx])` (#xxxx is the issue id) in your PR title for a better release log, e.g. `update entities encoding/decoding (fix #3899)`.
You will need [Node.js](http://nodejs.org) **version 8+**, [Java Runtime Environment](http://www.oracle.com/technetwork/java/javase/downloads/index.html) (for running Selenium server during e2e tests) and [yarn](https://yarnpkg.com/en/docs/install).
Commit messages should follow the [commit message convention](./COMMIT_CONVENTION.md) so that changelogs can be automatically generated. Commit messages will be automatically validated upon commit. If you are not familiar with the commit message convention, you can use `npm run commit` instead of `git commit`, which provides an interactive CLI for generating proper commit messages.
The default test script will do the following: lint with ESLint -> type check with Flow -> unit tests with coverage -> e2e tests. **Please make sure to have this pass successfully before submitting a PR.** Although the same tests will be run against your PR on the CI server, it is better to have it working locally.
- **`scripts`**: contains build-related scripts and configuration files. Usually, you don't need to touch them. However, it would be helpful to familiarize yourself with the following files:
-`scripts/config.js`: contains the build configurations for all files found in `dist/`. Check this file if you want to find out the entry source file for a dist file.
- **`dist`**: contains built files for distribution. Note this directory is only updated when a release happens; they do not reflect the latest changes in development branches.
- **`flow`**: contains type declarations for [Flow](https://flowtype.org/). These declarations are loaded **globally** and you will see them used in type annotations in normal source code.
- **`packages`**: contains `vue-server-renderer` and `vue-template-compiler`, which are distributed as separate NPM packages. They are automatically generated from the source code and always have the same version with the main `vue` package.
- **`test`**: contains all tests. The unit tests are written with [Jasmine](http://jasmine.github.io/2.3/introduction.html) and run with [Karma](http://karma-runner.github.io/0.13/index.html). The e2e tests are written for and run with [Nightwatch.js](http://nightwatchjs.org/).
The compiler consists of a parser (converts template strings to element ASTs), an optimizer (detects static trees for vdom render optimization), and a code generator (generate render function code from element ASTs). Note that codegen directly generates code strings from the element AST - it's done this way for smaller code size because the compiler is shipped to the browser in the standalone build.
The Vue 2.0 core is platform-agnostic. That is, the code inside `core` is able to be run in any JavaScript environment, be it the browser, Node.js, or an embedded JavaScript runtime in native applications.
Each platform module contains three parts: `compiler`, `runtime` and `server`, corresponding to the three directories above. Each part contains platform-specific modules/utilities which are imported and injected to the core counterparts in platform-specific entry files. For example, the code implementing the logic behind `v-bind:class` is in `platforms/web/runtime/modules/class.js` - which is imported in `entries/web-runtime.js` and used to create the browser-specific vdom patching function.
As a pure community-driven project without major corporate backing, we also welcome financial contributions via GitHub Sponsors and OpenCollective. Please consult the [Sponsor Page](https://vuejs.org/sponsor/) for more details.
