一系列的 JavaScript 项目最佳实践

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2017-07-09
原文链接:github.com

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While developing a new project is like rolling on a green field for you, maintaining it is a potential dark twisted nightmare for someone else. Here's a list of guidelines we've found, written and gathered that (we think) works really well with most JavaScript projects here at hive. If you want to share a best practice, or think one of these guidelines should be removed, feel free to share it with us.

1. Git

1.1 Git Workflow

We use Feature-branch-workflow with Interactive Rebasing and some elements of Gitflow (naming and having a develop branch). The main steps are as follow:

  • Checkout a new feature/bug-fix branch
    git checkout -b <branchname>
  • Make Changes
    git add
    git commit -m "<description of changes>"
  • Sync with remote to get changes you’ve missed
    git checkout develop
    git pull
  • Update your feature branch with latest changes from develop by interactive rebase (Here is why)
    git checkout <branchname>
    git rebase -i develop
  • If you don’t have conflict skip this step. If you have conflicts, resolve them and continue rebase
    git add <file1> <file2> ...
    git rebase --continue
  • Push your branch. Rebase will change history, so you'll have to use -f to force changes into the remote branch. If someone else is working on your branch, use the less destructive --force-with-lease (Here is why).
    git push -f
  • Make a Pull Request.
  • Pull request will be accepted, merged and close by reviewer.
  • Remove your local feature branch if you're done.

1.2 Some Git Rules

There are a set of rules to keep in mind:

  • Perform work in a feature branch.
  • Make pull requests to develop
  • Never push into develop or master branch.
  • Update your develop and do a interactive rebase before pushing your feature and making a Pull Request
  • Resolve potential conflicts while rebasing and before making a Pull Request
  • Delete local and remote feature branches after merging.
  • Before making a Pull Request, make sure your feature branch builds successfully and passes all tests (including code style checks).
  • Use this .gitignore file.
  • Protect your develop and master branch (How to in Github and Bitbucket).

1.3 Writing good commit messages

Having a good guideline for creating commits and sticking to it makes working with Git and collaborating with others a lot easier. Here are some rules of thumb (source):

  • Separate the subject from the body with a blank line
  • Limit the subject line to 50 characters
  • Capitalize the subject line
  • Do not end the subject line with a period
  • Use imperative mood in the subject line
  • Wrap the body at 72 characters
  • Use the body to explain what and why as opposed to how

2. Documentation

  • Use this template for README.md, Feel free to add uncovered sections.
  • For projects with more than one repository, provide links to them in their respective README.md files.
  • Keep README.md updated as project evolves.
  • Comment your code. Try to make it as clear as possible what you are intending with each major section.
  • If there is an open discussion on github or stackoverflow about the code or approach you're using, include the link in your comment,
  • Don't use commenting as an excuse for a bad code. Keep your code clean.
  • Don't use clean code as an excuse to not comment at all.
  • Comment even small sections of code if you think it's not self explanatory.
  • Keep comments relevant as your code evolves.

3. Environments

  • Depending on project size, define separate development, test and production environments.
  • Load your deployment specific configurations from environment variables and never add them to the codebase as constants, look at this sample.
  • Your config should be correctly separated from the app internals as if the codebase could be made public at any moment. Use .env files to store your variables and add them to .gitignore to be excluded from your code base because of course, you want the environment to provide them. Instead commit a .env.example which serves as a guide for developers to know which environment variables the project needs. It is important to remember that this setup should only be used for development. For production you should still set your environment variables in the standard way.
  • It’s recommended to validate environment variables before your app starts. Look at this sample using joi to validate provided values.

3.1 Consistent dev environments:

  • Set engines in package.json to specify the version of node your project works on.
  • Additionally, use nvm and create a .nvmrc in your project root. Don't forget to mention it in the documentation
  • You can also use a preinstall script that checks node and npm versions
  • Use Docker images provided it doesn't make things more complicated
  • Use local modules instead of using globally installed modules

4. Dependencies

Before using a package, check its GitHub. Look for the number of open issues, daily downloads and number of contributors as well as the date the package was last updated.

  • If less known dependency is needed, discuss it with the team before using it.
  • Keep track of your currently available packages: e.g., npm ls --depth=0 (documentation).
  • See if any of your packages have become unused or irrelevant: depcheck (documentation).
  • Check download statistics to see if the dependency is heavily used by the community: npm-stat (documentation).
  • Check to see if the dependency has a good, mature version release frequency with a large number of maintainers: e.g., npm view async (documentation).
  • Always make sure your app works with the latest versions of dependencies without breaking: npm outdated (documentation).
  • Check to see if the package has known security vulnerabilities with, e.g., Snyk.

4.1 Consistent dependencies:

  • Use package-lock.json on npm@5 or higher
  • For older versions of npm, use —save --save-exact when installing a new dependency and create npm-shrinkwrap.json before publishing.
  • Alternatively you can use Yarn and make sure to mention it in README.md. Your lock file and package.json should have the same versions after each dependency update.
  • Read more here: package-locks | npm Documentation

5. Testing

  • Have a test mode environment if needed.
  • Place your test files next to the tested modules using *.test.js or *.spec.js naming convention, like module_name.spec.js
  • Put your additional test files into a separate test folder to avoid confusion.
  • Write testable code, avoid side effects, extract side effects, write pure functions
  • Don’t write too many tests to check types, instead use a static type checker
  • Run tests locally before making any pull requests to develop.
  • Document your tests, with instructions.

6. Structure and Naming

  • Organize your files around product features / pages / components, not roles

Bad

    .
    ├── controllers
    |   ├── product.js
    |   └── user.js
    ├── models
    |   ├── product.js
    |   └── user.js

Good

    .
    ├── product
    |   ├── index.js
    |   ├── product.js
    |   └── product.test.js
    ├── user
    |   ├── index.js
    |   ├── user.js
    |   └── user.test.js
  • Place your test files next to their implementation.
  • Put your additional test files to a separate test folder to avoid confusion.
  • Use a ./config folder. Values to be used in config files are provided by environment variables.
  • Put your scripts in a ./scripts folder. This includes bash and node scripts for database synchronisation, build and bundling and so on.
  • Place your build output in a ./build folder. Add build/ to .gitignore.
  • Use PascalCase' 'camelCase for filenames and directory names. Use PascalCase only for Components.
  • CheckBox/index.js should have the CheckBox component, as could CheckBox.js, but not CheckBox/CheckBox.js or checkbox/CheckBox.js which are redundant.
  • Ideally the directory name should match the name of the default export of index.js.

7. Code style

  • Use stage-1 and higher JavaScript (modern) syntax for new projects. For old project stay consistent with existing syntax unless you intend to modernise the project.
  • Include code style check before build process.
  • Use ESLint - Pluggable JavaScript linter to enforce code style.
  • We use Airbnb JavaScript Style Guide for JavaScript, Read more. Use the javascript style guide required by the project or your team.
  • We use Flow type style check rules for ESLint. when using FlowType.
  • Use .eslintignore to exclude file or folders from code style check.
  • Remove any of your eslint disable comments before making a Pull Request.
  • Always use //TODO: comments to remind yourself and others about an unfinished job.
  • Always comment and keep them relevant as code changes.
  • Remove commented block of code when possible.
  • Avoid js alerts in production.
  • Avoid irrelevant or funny comments, logs or naming (source code may get handed over to another company/client and they may not share the same banter).
  • Write testable code, avoid side effect, extract side effects, write pure functions.
  • Make your names search-able with meaningful distinctions avoid shortened names. For functions Use long, descriptive names. A function name should be a verb or a verb phrase, and it needs to communicate its intention.
  • Organize your functions in a file according to the step-down rule. Higher level functions should be on top and lower levels below. It makes it more natural to read the source code.

8. Logging

  • Avoid client-side console logs in production
  • Produce readable production logging. Ideally use logging libraries to be used in production mode (such as winston or node-bunyan).

9 API design

Follow resource-oriented design. This has three main factors: resources, collection, and URLs.

  • A resource has data, relationships to other resources, and methods that operate against it
  • A group of resources is called a collection.
  • URL identifies the online location of a resource.

9.1 API Naming

9.1.1 Naming URLs

  • /users a collection of users (plural nouns).
  • /users/id a resource with information about a specific user.
  • A resource always should be plural in the URL. Keep verbs out of your resource URLs.
  • Use verbs for non-resources. In this case, your API doesn't return any resources. Instead, you execute an operation and return the result to the client. Hence, you should use verbs instead of nouns in your URL to distinguish clearly the non-resource responses from the resource-related responses.

GET /translate?text=Hallo

9.1.2 Naming fields

  • The request body or response type is JSON then please follow camelCase to maintain the consistency.
  • Expose Resources, not your database schema details. You don't have to use your table_name for a resource name as well. Same with resource properties, they shouldn't be the same as your column names.
  • Only use nouns in your URL naming and don’t try to explain their functionality and only explain the resources (elegantly).

9.2 Operating on resources

9.2.1 Use HTTP methods

Only use nouns in your resource URLs, avoid endpoints like /addNewUser or /updateUser . Also avoid sending resource operations as a parameter. Instead explain the functionalities using HTTP methods:

  • GET Used to retrieve a representation of a resource.
  • POST Used to create new resources and sub-resources
  • PUT Used to update existing resources
  • PATCH Used to update existing resources. PATCH only updates the fields that were supplied, leaving the others alone
  • DELETE Used to delete existing resources

9.3 Use sub-resources

Sub resources are used to link one resource with another, so use sub resources to represent the relation. An API is supposed to be an interface for developers and this is a natural way to make resources explorable. If there is a relation between resources like employee to a company, use id in the URL:

  • GET /schools/2/students Should get the list of all students from school 2
  • GET /schools/2/students/31 Should get the details of student 31, which belongs to school 2
  • DELETE /schools/2/students/31 Should delete student 31, which belongs to school 2
  • PUT /schools/2/students/31 Should update info of student 31, Use PUT on resource-URL only, not collection
  • POST /schools Should create a new school and return the details of the new school created. Use POST on collection-URLs

9.4 API Versioning

When your APIs are public for other third parties, upgrading the APIs with some breaking change would also lead to breaking the existing products or services using your APIs. Using versions in your URL can prevent that from happening: http://api.domain.com/v1/schools/3/students

9.5 Send feedbacks

9.5.1 Errors

Response messages must be self descriptive. A good error message response might look something like this:

{
"code": 1234,
"message" : "Something bad happened",
"description" : "More details"
}

or for validation errors:

{
  "code" : 2314,
  "message" : "Validation Failed",
  "errors" : [
    {
      "code" : 1233,
      "field" : "email",
      "message" : "Invalid email"
    },
    {
       "code" : 1234,
       "field" : "password",
       "message" : "No password provided"
    }
  ]
}

Note: Keep security exception messages as generic as possible. For instance, Instead of saying ‘incorrect password’, you can reply back saying ‘invalid username or password’ so that we don’t unknowingly inform user that username was indeed correct and only password was incorrect.

9.5.2 Align your feedback with HTTP codes.

The client and API worked (success – 2xx response code)
  • 200 OK This HTTP response represents success for GET, PUT or POST requests.
  • 201 Created This status code should be returned whenever a new instance is created. E.g on creating a new instance, using POST method, should always return 201 status code.
  • 204 No Content represents the request was successfully processed, but has not returned any content. DELETE can be a good example of this. If there is any error, then the response code would be not be of 2xx Success Category but around 4xx Client Error category.
The client application behaved incorrectly (client error – 4xx response code)
  • 400 Bad Request indicates that the request by the client was not processed, as the server could not understand what the client is asking for.
  • 401 Unauthorized indicates that the request lacks valid credentials needed to access the needed resources, and the client should re-request with the required credentials.
  • 403 Forbidden indicates that the request is valid and the client is authenticated, but the client is not allowed access the page or resource for any reason.
  • 404 Not Found indicates that the requested resource was not found.
  • 406 Not Acceptable A response matching the list of acceptable values defined in Accept-Charset and Accept-Language headers cannot be served.
  • 410 Gone indicates that the requested resource is no longer available and has been intentionally and permanently moved.
The API behaved incorrectly (server error – 5xx response code)
  • 500 Internal Server Error indicates that the request is valid, but the server could not fulfill it due to some unexpected condition.
  • 503 Service Unavailable indicates that the server is down or unavailable to receive and process the request. Mostly if the server is undergoing maintenance or facing a temporary overload.

9.6 Resource parameters and metadata

  • Provide total numbers of resources in your response
  • The amount of data the resource exposes should also be taken into account. The API consumer doesn't always need the full representation of a resource.Use a fields query parameter that takes a comma separated list of fields to include:
    GET /student?fields=id,name,age,class
    
  • Pagination, filtering and sorting don’t need to be supported by default for all resources. Document those resources that offer filtering and sorting.

9.7 API security

9.7.1 TLS

To secure your web API authentication, all authentications should use SSL. OAuth2 requires the authorization server and access token credentials to use TLS. Switching between HTTP and HTTPS introduces security weaknesses and best practice is to use TLS by default for all communication. Throw an error for non-secure access to API URLs.

9.7.2 Rate limiting

If your API is public or have high number of users, any client may be able to call your API thousands of times per hour. You should consider implementing rate limit early on.

9.7.3 Input Validation

It's difficult to perform most attacks if the allowed values are limited.

  • Validate required fields, field types (e.g. string, integer, boolean, etc), and format requirements. Return 400 Bad Request with details about any errors from bad or missing data.

  • Escape parameters that will become part of the SQL statement to protect from SQL injection attacks

  • As also mentioned before, don't expose your database scheme when naming your resources and defining your responses

9.7.4 URL validations

Attackers can tamper with any part of an HTTP request, including the URL, query string,

9.7.5 Validate incoming content-types.

The server should never assume the Content-Type. A lack of Content-Type header or an unexpected Content-Type header should result in the server rejecting the content with a 406 Not Acceptable response.

9.7.6 JSON encoding

A key concern with JSON encoders is preventing arbitrary JavaScript remote code execution within the browser or node.js, on the server. Use a JSON serialiser to entered data to prevent the execution of user input on the browser/server.

9.8 API documentation

  • Fill the API Reference section in README.md template for API.
  • Describe API authentication methods with a code sample
  • Explaining The URL Structure (path only, no root URL) including The request type (Method)

For each endpoint explain:

  • URL Params If URL Params exist, specify them in accordance with name mentioned in URL section
Required: id=[integer]
Optional: photo_id=[alphanumeric]
  • If the request type is POST, provide a working examples. URL Params rules apply here too. Separate the section into Optional and Required.
  • Success Response, What should be the status code and is there any return data? This is useful when people need to know what their callbacks should expect!
    Code: 200
    Content: { id : 12 }
    
  • Error Response, Most endpoints have many ways to fail. From unauthorised access, to wrongful parameters etc. All of those should be listed here. It might seem repetitive, but it helps prevent assumptions from being made. For example
    {
        "code": 403,
        "message" : "Authentication failed",
        "description" : "Invalid username or password"
    }   

9.8.1 API design tools

There are lots of open source tools for good documentation such as API Blueprint and Swagger.

10. Licensing

Make sure you use resources that you have the rights to use. If you use libraries, remember to look for MIT, Apache or BSD but if you modify them, then take a look into licence details. Copyrighted images and videos may cause legal problems.


Sources: RisingStack Engineering, Mozilla Developer Network, Heroku Dev Center, Airbnb/javascript Atlassian Git tutorials

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