Code Style Guide

As a community, Reaction follows guidelines for code style and naming conventions for variables, methods and filenames. The guide also includes tips on working with libraries in Reaction, like React, MongoDB, lodash and more.

Syntax and style conventions

Our rules are similar to Airbnb JavaScript Style Guide and Meteor Code Style, with a few custom Reaction-specific rules:

Always double-quote strings
Give methods space
Add spaces around brackets
120 character line-length
imports should be listed in this order, as enforced by ESLint:
1. Built-in: Built-in Node modules
2. External: External packages, ordered by:
  - React packages
  - External npm modules
  - Meteor Core packages
  - Meteor Atmosphere packages
3. Internal: Internal Reaction modules
4. Parent: Modules from a parent directory
5. Sibling: Modules from the same or sibling directories
6. Index: Index of the current directory

Other Reaction-specific rules are checked using various linting libraries. Find all the rules in the code:

@reactioncommerce/eslint-config - This Reaction Commerce ESLint config checks JavaScript style, including ES2015, React and Babel, across all Reaction apps.
.jsbeautifyrc - JS Beautifier automates code formatting
.editorconfig - Editor Config standardizes file formatting

To see the rules in action, run npm run lint or npx eslint . from the command line or use ESLint code editor tools.

Naming conventions

Use hyphens to separate words in names

File and directory names should be hyphenated. Not all operating systems are case sensitive, so avoid having two files named the same with differing case.

Names of folders and files should be:

Lowercased
Alphanumeric characters
Hyphenated to join more words
Avoid camelCase, undescore_casing
Files may use multiple . as needed

/ui-grid/
/example-payment-method/
/social/
/bootstrap.rtl.js
/index.js

Don't

/reactionpackagename/
/address_book/
/addressBook/
/settingsContainer.js
/addressBook.js
/address_book.js

Working with packages

Create strong package names

Namespace package folders in this format: <functionality>-<package-name> or <organization-name>-<package-name>

/imports/plugins/custom/payments-authnet
/imports/plugins/included/connectors-shopify
/imports/plugins/custom/connectors-magento
/reaction-paypal/
/yourorg-your-package/

Group related files together into folders

If there are multiple files that provide functionality that is broken down across multiple files, these files should be grouped within a folder.

If the files are stand-alone and the name needs to represent functionality, you can use a hyphen for the separator.

/container/settings.js
/container/settings.html
/container/ <more files>

// or

/settings-container.js
/settings-container.html

Don't

/container/settings-containers.js
/container/settingsContainer.html
settingsContainer.js

JavaScript style recommendations

Variables

Variable names should be:

Meaningful. Avoid single-letter variables.
Use error, instead of e or err
Variables that contain a boolean value should use a isThisTrue style.
Variables that return arrays should be plural.

Publication names should:

Use TitleCase

Working with variables:

Use const except when a variable is being reassigned.
Use string template notation, ${thisVariable} is true over string concatenation

Methods

Naming methods:

Methods names should use a verb/noun style when possible, e.g. checkConfiguration or addToCart.
When naming multiple methods acting on the same resource should follow this style, e.g. cart/items/add, cart/items/remove
Methods that return a single value should be singular.
Methods whose main purpose is to return a value should use the get prefix, e.g. getShop.

Working with methods:

Avoid ternary operators and one-line if statements (except in React componenets)
Use parenthesis around all method arguments:

// do - use () around the method arguments
cartItems.find((item) => item.status === picked)

// don't
cartItems.find(item => item.status === picked)

When specifying a callback, always use the parenthesis to indicate the argument being accepted over the bare arrow-function form. This way, it's clear it's not another argument to the original function:

// do - explicitly use a () in the callback function
thisMethodTakesACallback(arg1, arg2, (result) => {
  dostuff();
});

// don't
thisMethodTakesACallback(arg1, arg2, result => {
  doStuff
});

When breaking arrow functions into multiple lines, use curly brackets and a return:

// do - explicitly use a return
cartItems.find((item) => {
  return item.status === status;
})

// don't
cartItems.find(
  (item) => item.status === status
)

Working with collections

Be explicit in querying:

// do - explicitly state the key being queried
Products.findOne({ _id: "abc123" })

// don't
Products.findOne("abc123")

Using native JavaScript

Use native JavaScript over libraries like lodash and Underscore whenever there is a suitable replacement.

Replace _.map, with Array.prototype.map
Replace _.reduce, with Array.prototype.reduce
Replace _.filter, with Array.prototype.filter
Replace _.isArray, with Array.isArray
Replace _.extend with Object.assign
Replace _.find with Array.prototype.find
Replace _.keys and _.values, with Object.keys and Object.values
Replace _.first, _.rest and _.restParam, with destructuring syntax
Replace _.uniq, with using a Set: [...new Set(cartItems.map((item) => item.product._id))]
Replace pluck from Underscore with .map:

const people = [{name: "George"}, {name: "Katherine"}, {name: "Kip"}]
_.pluck(people, name) => people.map((person) => person.name)

Replace _.each, _.forEach, with Array.prototype.forEach or loop over an object with:

sum = 0;
lastKey = undefined;
for (const [key, value] of Object.entries(foo)) {
  sum += value;
  lastKey = key;
}

Working with React

Use isRequired for validating PropTypes
Use the return shorthand with arrow functions in React components:

// do

const MyComponent = ({ title, content }) => (
  <div>
    <h1>{title}</h1>
    <div>{content}/</div>
  </div>
);

// don't

const MyComponent = ({ title, content }) => {
  return (
    <div>
      <h1>{title}</h1>
      <div>{content}/</div>
    </div>
  );
}

Use the return shorthand with arrow function when iterating over arrays in a component:

    const MyThings = ({ things }) => (
      <ul>
        {things.map((thing) => <li>{thing}</li>)}
      </ul>
    );

    // or

    const MyThings = ({ things }) => (
      <ul>
        {things.map((thing) => (
          <li>{thing}</li>
        ))}
      </ul>
    );

Copy conventions

Use sentence casing

When writing user interface copy for Reaction, use sentence casing. This includes copy for titles, buttons, alerts, form inputs, form placeholders and copy elsewhere used throughout the application.

Copy should be:

Have the first letter capitalized.
No other words should be capitalized.
Example: Your orders instead of Your Orders

// do
<h3 class="panel-title">Your orders</h3>
<Components.Translation defaultValue="Payment method" i18nKey={"cartCompleted.paymentMethod"} />

// don't
<h3 class="panel-title">Your Orders</h3>
<Components.Translation defaultValue="Payment Method" i18nKey={"cartCompleted.paymentMethod"} />

Reaction Docs

2.0.0-rc.1

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