CI workflow (trekhleb/javascript-algorithms)

The CI workflow from trekhleb/javascript-algorithms, explained and optimized by Latchkey.

What it does

This is the CI workflow from the trekhleb/javascript-algorithms repository, a real project running GitHub Actions. It is shown here with attribution under its MIT license.

Below, Latchkey shows a faster, safer version produced by its optimization engine.

The workflow

name: CI

on:
  push:
    branches: [ master ]
  pull_request:
    branches: [ master ]

jobs:
  test:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        node-version: [ 22.x ]

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Setup Node.js ${{ matrix.node-version }}
        uses: actions/setup-node@v4
        with:
          node-version: ${{ matrix.node-version }}

      - name: Install dependencies
        run: npm i

      - name: Run linting
        run: npm run lint

      - name: Run tests
        run: npm run coverage

      - name: Upload coverage to Codecov
        uses: codecov/codecov-action@v4

The same workflow, on Latchkey

Estimated ~20% faster on cache hits, plus fewer wasted runs and a safer supply chain. Added and changed lines are highlighted.

name: CI
 
on:
  push:
    branches: [ master ]
  pull_request:
    branches: [ master ]
 
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true
 
jobs:
  test:
    timeout-minutes: 30
    runs-on: latchkey-small
    strategy:
      matrix:
        node-version: [ 22.x ]
 
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
 
      - name: Setup Node.js ${{ matrix.node-version }}
        uses: actions/setup-node@v4
        with:
          cache: 'npm'
          node-version: ${{ matrix.node-version }}
 
      - name: Install dependencies
        run: npm i
 
      - name: Run linting
        run: npm run lint
 
      - name: Run tests
        run: npm run coverage
 
      - name: Upload coverage to Codecov
        uses: codecov/codecov-action@v4
 

What changed

• Run on Latchkey managed runners with one line (runs-on), which apply the fixes below automatically and self-heal transient failures. This example uses latchkey-small; pick the runner size that fits the job.
• Cancel superseded runs when a branch or PR gets a newer push.
• Cache dependency installs on the setup step so they are served from cache.
• Add a job timeout so a hung step cannot burn hours of runner time.

1 third-party action is referenced by a movable tag. Pin it to the commit SHA (Latchkey resolves and applies this automatically) so a repointed tag cannot change what runs.

This workflow runs 1 job per trigger. On Latchkey the same minutes cost up to 58% less than GitHub-hosted, with zero queue time.

Actions used in this workflow