Format and lint

.eslintignore

@@ -1,17 +1 @@
-alphametics
-connect
-diamond
-food-chain
-forth
-grade-school
-grains
-list-ops
-nth-prime
-palindrome-products
-queen-attack
-rational-numbers
-saddle-points
-secret-handshake
-sublist
-twelve-days
-variable-length-quantity
+

.gitattributes

@@ -1 +1 @@
-* text=auto
+* text=auto eol=lf

.github/CODEOWNERS

@@ -1,5 +1,6 @@
-# Maintainers 
+# Maintainers
 config/maintainers.json @exercism/maintainers-admin
 
 # Code owners
 .github/CODEOWNERS      @exercism/maintainers-admin
+.github/workflows       @exercism/javascript

.github/workflows/codeql.yml

@@ -3,7 +3,7 @@
 #
 # You may wish to alter this file to override the set of languages analyzed,
 # or to provide custom queries or build logic.
-name: "codeql"
+name: 'codeql'
 
 on:
   push:
@@ -12,7 +12,7 @@ on:
     # The branches below must be a subset of the branches above
     branches: [master]
   schedule:
-    - cron: "0 14 * * 5"
+    - cron: '0 14 * * 5'
 
 jobs:
   analyze:
@@ -23,7 +23,7 @@ jobs:
       matrix:
         # Override automatic language detection by changing the below list
         # Supported options are ['csharp', 'cpp', 'go', 'java', 'javascript', 'python']
-        language: ["javascript"]
+        language: ['javascript']
         # Learn more...
         # https://docs.github.com/en/github/finding-security-vulnerabilities-and-errors-in-your-code/configuring-code-scanning#overriding-automatic-language-detection
 

.github/workflows/format-code.yml

@@ -0,0 +1,110 @@
+name: 'Format code'
+
+on:
+  issue_comment:
+    types: [created]
+
+jobs:
+  format:
+    name: 'Format code'
+    runs-on: ubuntu-latest
+    if: github.event.issue.pull_request != '' && contains(github.event.comment.body, '/format')
+    steps:
+      - name: 'Post acknowledgement that it will format code'
+        continue-on-error: true # Never fail the build if this fails
+        uses: actions/github-script@6e5ee1dc1cb3740e5e5e76ad668e3f526edbfe45 # 2.0.0
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            github.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: 'The "Format code" action has started running.'
+            })
+
+      - name: 'Download PR data'
+        run: |
+          PR_DATA="/tmp/pr.json"
+
+          jq -r ".issue.pull_request.url" "$GITHUB_EVENT_PATH" | \
+            xargs curl --header 'authorization: Bearer ${{ secrets.GITHUB_TOKEN }}' -o "$PR_DATA" --url
+
+      - name: 'Check fork status'
+        id: fork_status
+        run: |
+          IS_FORK="$(jq '.head.repo.fork' "/tmp/pr.json")"
+          echo "::set-output name=fork::$IS_FORK"
+
+      - name: 'Setup SSH deploy key'
+        if: steps.fork_status.outputs.fork == 'false'
+        run: |
+          mkdir ~/.ssh
+          echo "${{ secrets.DEPLOY_KEY }}" > ~/.ssh/id_ed25519
+          chmod 600 ~/.ssh/id_ed25519
+
+      - name: 'Checkout code'
+        run: |
+          PR_DATA="/tmp/pr.json"
+
+          HEAD_REF=$(jq -r ".head.ref" "$PR_DATA")
+
+          if [ ${{ steps.fork_status.outputs.fork }} == "false" ]; then
+            echo "::debug::Setting up repo using SSH"
+            HEAD_REPO=$(jq -r '.head.repo.ssh_url' "$PR_DATA")
+          else
+            echo "::debug::Setting up repo using HTTPS"
+            HEAD_REPO=$(jq -r '.head.repo.clone_url | sub("https://"; "https://x-access-token:${{ secrets.GITHUB_TOKEN }}@")' "$PR_DATA")
+          fi
+
+          git clone $HEAD_REPO .
+          git checkout -b "$HEAD_REF" "origin/$HEAD_REF"
+
+      - name: 'Format code'
+        run: ./bin/format.sh
+        env:
+          EXERCISM_PRETTIER_VERSION: '2.1.2'
+
+      - name: 'Commit formatted code'
+        run: |
+          # Check if there is nothing to commit (i.e. no formatting changes made)
+          if [ -z "$(git status --porcelain)" ]; then
+            echo "Code is already formatted correctly"
+            exit 0
+          fi
+
+          # Setup the git user (required to commit anything)
+          git config --global user.email "github-actions[bot]@users.noreply.github.com"
+          git config --global user.name "github-actions[bot]"
+
+          # Commit the changes made by prettier
+          git add .
+          git commit -m "[CI] Format code"
+          git push
+
+      - name: 'Post acknowledgement that it has formatted the code'
+        continue-on-error: true # Never fail the build if this fails
+        uses: actions/github-script@6e5ee1dc1cb3740e5e5e76ad668e3f526edbfe45 # 2.0.0
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            github.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: 'The "Format code" action has finished running.'
+            })
+
+      - name: 'Post reminder to trigger build manually'
+        continue-on-error: true # Never fail the build if this fails
+        if: steps.fork_status.outputs.fork == 'true'
+        uses: actions/github-script@6e5ee1dc1cb3740e5e5e76ad668e3f526edbfe45 # 2.0.0
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            github.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: 'For security reasons, `/format` does not trigger CI builds when the PR has been submitted from a fork. If checks were not passing due to code format, trigger a build to make the required checks pass, through one of the following ways:\n\n- Push an empty commit to this branch: `git commit --allow-empty -m "Trigger builds"`.\n- Close and reopen the PR.\n- Push a regular commit to this branch.'
+            })

.github/workflows/verify-code-formatting.yml

@@ -0,0 +1,18 @@
+name: javascript / format
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Checkout code'
+        uses: actions/checkout@v2
+
+      - name: 'Verify formatting of all files'
+        run: ./bin/check-formatting.sh
+        env:
+          EXERCISM_PRETTIER_VERSION: '2.2.1'

.prettierignore

@@ -0,0 +1,2 @@
+exercises/**/README.md
+!/README.md

.prettierrc

@@ -0,0 +1,5 @@
+{
+  "semi": true,
+  "singleQuote": true,
+  "endOfLine": "lf"
+}

CONTRIBUTING.md

@@ -6,27 +6,29 @@ We welcome contributions of all sorts and sizes, from reporting issues to submit
 
 ---
 
-- [Code of Conduct](#code-of-conduct)
-- [Exercises](#exercises)
-  - [New exercise](#new-exercise)
-    - [Implementing existing exercise](#implementing-existing-exercise)
-    - [ Creating a track-specific exercise](#creating-a-track-specific-exercise)
-  - [Existing exercises](#existing-exercises)
-    - [Improving the README.md](#improving-the-readmemd)
-    - [Syncing the exercise](#syncing-the-exercise)
-    - [Improving or adding mentor notes](#improving-or-adding-mentor-notes)
-    - [Improving or adding automated test analyzers](#improving-or-adding-automated-test-analyzers)
-- [Documentation](#documentation)
-- [Tools](#tools)
-  - [Fetch `configlet`](#fetch-configlet)
-  - [Fetch `canonical_data_syncer`](#fetch-canonical-data-syncer)
-  - [Scripts](#scripts)
-    - [`lint`](#lint)
-    - [`test`](#test)
-    - [`sync`](#sync)
-    - [`checksum`](#checksum)
-    - [`ci-check`](#ci-check)
-    - [`ci`](#ci)
+- [Contributing](#contributing)
+  - [Code of Conduct](#code-of-conduct)
+  - [Exercises](#exercises)
+    - [New exercise](#new-exercise)
+      - [Implementing existing exercise](#implementing-existing-exercise)
+      - [Creating a track-specific exercise](#creating-a-track-specific-exercise)
+    - [Existing exercises](#existing-exercises)
+      - [Improving the README.md](#improving-the-readmemd)
+      - [Syncing the exercise](#syncing-the-exercise)
+      - [Improving or adding mentor notes](#improving-or-adding-mentor-notes)
+      - [Improving or adding automated test analyzers](#improving-or-adding-automated-test-analyzers)
+  - [Documentation](#documentation)
+  - [Tools](#tools)
+    - [Fetch configlet](#fetch-configlet)
+    - [Fetch canonical data syncer](#fetch-canonical-data-syncer)
+    - [Scripts](#scripts)
+      - [`format`](#format)
+      - [`lint`](#lint)
+      - [`test`](#test)
+      - [`sync`](#sync)
+      - [`checksum`](#checksum)
+      - [`ci-check`](#ci-check)
+      - [`ci`](#ci)
 
 ---
 
@@ -70,6 +72,7 @@ If there is no such issue, you may open one. The baseline of work is as follows:
 1. Run the tests locally, using `scripts/test`: `ASSIGNMENT=slug npx babel-node scripts/test`.
 1. Run the linter locally, using `scripts/lint`: `ASSIGNMENT=slug npx babel-node scripts/lint`.
 1. Create an entry in `config.json`: a unique _new_ UUID (you can use the `configlet uuid` tool to generate one, scroll down to [tools](#tools) to see how you can get it), give it a difficulty (should be similar to similar exercises), and make sure the _order_ of the file is sane. Currently the file is ordered first on core - non core, then on difficulty low to high, and finally lexographically.
+1. Format the files, using `scripts/format`: `npx babel-node scripts/format`.
 
 The final step is opening a Pull Request, with these items all checked off. Make sure the tests run and the linter is happy. It will run automatically on your PR.
 
@@ -128,6 +131,8 @@ You'll need LTS or higher NodeJS in order to contribute to the _code_ in this re
 - `jest` to run all the test files on all example implementations
 - `babel` to transpile everything so it works _regardless of your version of NodeJS_.
 
+We also use `prettier` to format the files. **Prettier is _NOT_ installed when using `npm install`**, because the CI will enforce a certain version. Instead use `npx babel-node scripts/format` to run prettier. If you want to auto-format using your editor, match the version in the GitHub Workflow `verify-code-formatting.yml`.
+
 ### Fetch configlet
 
 If you'd like to download [configlet][configlet], you can use the [`fetch-configlet`][bin-fetch-configlet] binary. It will run on Linux, Mac OSX and Windows, and download `configlet` to your local drive. Find more information about [configlet][configlet] [here][configlet].
@@ -155,6 +160,19 @@ If you'd like to download [`canonical_data_syncer`][canonical-data-syncer], you
 
 We have various `scripts` for you in order to aid with maintaining and contributing to this repository.
 
+#### `format`
+
+```js
+/*
+ * Run this script (from root directory): npx babel-node scripts/format
+ *
+ * This runs `prettier` on all applicable files, FORCES using the same version
+ * as the CI uses to check if the files have been formatted.
+ */
+```
+
+Use this action to format all the files using the correct version of prettier. If you want your editor to do this automatically, make sure you install `prettier` (e.g. `npm install [email protected]`), where the version matches `.github/workflows/verify-code-formatting.yml`.
+
 #### `lint`
 
 ```js

README.md

@@ -16,7 +16,7 @@ contribute to this track. It also has a list of tools you can use, of which the
 
 ## Running the test suite
 
-This runs `jest` tests for all sample solutions. This *does not* use the regular way to run `jest`, because the example solution files must be renamed to be imported correctly into the test files.
+This runs `jest` tests for all sample solutions. This _does not_ use the regular way to run `jest`, because the example solution files must be renamed to be imported correctly into the test files.
 
 ```shell
 npx babel-node scripts/test
@@ -36,18 +36,17 @@ ASSIGNMENT=two-fer npx babel-node scripts/test
 
 ## Related repositories
 
-* [Website Copy][git-website-copy] (Mentor Notes)
-* [The JavaScript Analyzer][git-javascript-analyzer] (Automated Code Analysis)
-* [The JavaScript Test Runner][git-javascript-test-runner]
-* [The TypeScript track][git-typescript]
-* [The TypeScript Analyzer][git-typescript-analyzer]
+- [Website Copy][git-website-copy] (Mentor Notes)
+- [The JavaScript Analyzer][git-javascript-analyzer] (Automated Code Analysis)
+- [The JavaScript Test Runner][git-javascript-test-runner]
+- [The TypeScript track][git-typescript]
+- [The TypeScript Analyzer][git-typescript-analyzer]
 
 [web-exercism]: https://exercism.io
 [git-configlet]: https://github.com/exercism/docs/blob/master/language-tracks/configuration/configlet.md
 [bin-fetch-configlet]: https://github.com/exercism/javascript/blob/master/bin/fetch-configlet
 [file-config]: https://github.com/exercism/javascript/blob/master/config.json
 [file-contributing]: https://github.com/exercism/javascript/blob/master/CONTRIBUTING.md
-
 [git-javascript]: https://github.com/exercism/javascript
 [git-javascript-analyzer]: https://github.com/exercism/javascript-analyzer
 [git-javascript-test-runner]: https://github.com/exercism/javascript-test-runner

babel.config.js

@@ -1,15 +1,15 @@
 module.exports = {
   presets: [
     [
-      "@babel/preset-env",
+      '@babel/preset-env',
       {
         targets: {
-          node: "current",
+          node: 'current',
         },
-        useBuiltIns: "entry",
+        useBuiltIns: 'entry',
         corejs: 3,
       },
     ],
   ],
-  plugins: ["@babel/plugin-syntax-bigint"],
+  plugins: ['@babel/plugin-syntax-bigint'],
 };

bin/check-formatting.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+npx "prettier@$EXERCISM_PRETTIER_VERSION" --check "**/*.{js,jsx,ts,tsx,css,sass,scss,html,json,md,yml}"

bin/format.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+
+if [ -z "$EXERCISM_PRETTIER_VERSION" ]; then
+	echo "This script requires the EXERCISM_PRETTIER_VERSION variable to work."
+	echo "Please see https://github.com/exercism/v3/blob/master/docs/maintainers/style-guide.md for guidance."
+	exit 1
+fi
+
+npx "prettier@$EXERCISM_PRETTIER_VERSION" --write "**/*.{js,jsx,ts,tsx,css,sass,scss,html,json,md,yml}"