Hi! I’m really excited that you are interested in contributing to Vue.js. Before submitting your contribution though, please make sure to take a moment and read through the following guidelines.
- The `master` branch is basically just a snapshot of the latest stable release. All development should be done in dedicated branches. **Do not submit PRs against the `master` branch.**
- Provide convincing reason to add this feature. Ideally you should open a suggestion issue first and have it greenlighted before working on it.
- If fixing a bug:
- If you are resolving a special issue, add `(fix #xxxx[,#xxx])` (#xxxx is the issue id) in your PR title for a better release log, e.g. `update entities encoding/decoding (fix #3899)`.
- Provide detailed description of the bug in the PR. Live demo preferred.
- Add appropriate test coverage if applicable.
## Development Setup
You will need [Node.js](http://nodejs.org)**version 6+** and [Java Runtime Environment](http://www.oracle.com/technetwork/java/javase/downloads/index.html)(needed for running Selenium server during e2e tests).
After cloning the repo, run:
``` bash
$ npm install
& npm run setup
```
The `setup` script links two git hooks:
-`pre-commit`: runs ESLint on staged files.
-`commit-msg`: validates commit message format (see below).
### Commiting Changes
Commit messages should follow the [commit message convention](./COMMIT_CONVENTION.md) so that changelogs can be automatically generated. If git hooks have been properly linked, commit messages will be automatically validated upon commit. It is recommended to use `npm run commit` instead of `git commit`, which provides an interactive CLI for generating proper commit messages.
### Commonly used NPM scripts
``` bash
# watch and auto re-build dist/vue.js
$ npm run dev
# watch and auto re-run unit tests in Chrome
$ npm run dev:test
# build all dist files, including npm packages
$ npm run build
# run the full test suite, include linting / type checking
$ npm test
```
There are some other scripts available in the `scripts` section of the `package.json` file.
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 beforehand.
## Project Structure
-**`build`**: contains build-related configuration files. In most cases you don't need to touch them. However, it would be helpful to familiarize yourself with the following files:
-`build/alias.js`: module import aliases used across all source code and tests.
-`build/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.
See [dist/README.md](https://github.com/vuejs/vue/blob/dev/dist/README.md) for more details on dist files.
-**`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/).
-**`src`**: contains the source code, obviously. The codebase is written in ES2015 with [Flow](https://flowtype.org/) type annotations.
-**`compiler`**: contains code for the template-to-render-function compiler.
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 the 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 - which means code inside `core` should be able to run in any JavaScript environment, be it the browser, Node.js, or an embedded JavaScript runtime in native applications.
- **`observer`**: contains code related to the reactivity system.
- **`vdom`**: contains code related to vdom element creation and patching.
- **`instance`**: contains Vue instance constructor and prototype methods.
- **`global-api`**: as the name suggests.
- **`components`**: universal abstract components. Currently `keep-alive` is the only one.
-**`server`**: contains code related to server-side rendering.
Entry files for dist builds are located in their respective platform directory.
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 then 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.
-**`sfc`**: contains single-file component (`*.vue` files) parsing logic. This is used in the `vue-template-compiler` package.
-**`shared`**: contains utilities shared across the entire codebase.
