Backend development cheat sheet (Node.js)

1. 1Node.js and TypeScript essentialsHow Node.js runs your code, how TypeScript describes it and how packages and frameworks fit together. Everything later in the sheet builds on these.6 concepts

   1. 1The event loopNode.js runs your JavaScript on one thread.
   2. 2Promises and async/awaitA Promise represents a value that arrives later.
   3. 3TypeScript types and interfacesTypeScript adds static types to JavaScript: interfaces and type aliases describe object shapes, unions list allowed values, and the compiler checks every use.
   4. 4npm, package.json and lockfilespackage.json lists dependencies and scripts; the lockfile pins the exact version of every package in the tree. npm, pnpm and Yarn all read them.
   5. 5NestJS controllers, providers and modulesNestJS is a structured framework on top of Express or Fastify.
   6. 6JavaScript core: values, scope and closuresPrimitives (string, number, boolean, null, undefined) are copied, while objects are passed by reference.

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2. 2Terminal and GitThe two tools every backend task starts with: moving around a machine in a shell, and keeping every change in version control.3 concepts

   1. 1Terminal essentialsA shell runs commands such as cd, ls, cat, grep and curl, and pipes (|) feed one command's output into the next.
   2. 2Git commits and branchesGit records snapshots of your project as commits.
   3. 3Pull requestsA pull request proposes merging a branch into main and shows the diff, CI results and review comments in one place.

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3. How HTTP worksWhat happens between a client and your server: finding it, connecting securely and exchanging requests and responses.6 conceptsOpens with credits
4. Relational databases and SQLModel data, query it by hand, index it for real queries, keep it consistent with transactions and understand what the ORM does for you.10 conceptsOpens with credits
5. Designing and building APIsTurn the database into a contract other programs rely on: resources, validation, errors, pagination, safe retries, versioning and documentation.10 conceptsOpens with credits
6. Authentication and API securityDecide who is calling and what they may do, store secrets safely and close the holes attackers try first.10 conceptsOpens with credits
7. Caching, queues and performanceMeasure first, then make the service fast: cache the right things, keep slow work out of the request path and use database connections wisely.10 conceptsOpens with credits
8. Testing, CI/CD and deploymentBuild the safety net that lets you change code without fear: tests against a real database, a pipeline on every push and a container you can deploy and roll back.10 conceptsOpens with credits
9. Architecture and reliabilityHow services are split, how they talk and how they fail, and the patterns that keep a system up and traceable when a dependency is slow or down.10 conceptsOpens with credits
10. 10Glossary, A to ZEvery concept in the sheet and the smaller terms it uses, in one list.176 terms

APIs, databases, auth, deploys.