Reference · 62 terms
Glossary
Every short form used across the series. Inside a lesson, hover or tap any dotted term to see the same entry in place.
JavaScript
- debounceDebounce
- Wait until calls stop for a set time, then run once. Good for search-as-you-type.Lesson 17 →
- microtaskMicrotask
- A small job (like a promise callback) that runs as soon as the current code finishes, before timers and rendering.Lesson 16 →
- polyfillPolyfill
- Code that adds a missing built-in feature to older environments.Lesson 17 →
- prototype chainPrototype chain
- The chain of objects JavaScript follows to find a property that is not on the object itself.Lesson 15 →
- structuredClonestructuredClone
- A built-in function that makes a deep copy of data, including Date, Map, Set and circular references. It cannot copy functions.Lesson 15 →
- throttleThrottle
- Run at most once in a set time, however many calls arrive. Good for scroll and resize handlers.Lesson 17 →
Frontend
- @layerCascade layer
- A CSS feature that sorts rules into ordered groups. A later layer wins over an earlier one, whatever the specificity.Lesson 1 →
- class-variance-authorityclass-variance-authority (cva)
- A small library for describing component variants (size, colour) as Tailwind class lists.Lesson 2 →
- container queryContainer query
- A CSS rule that changes styles based on the size of a parent container, not the whole screen.Lesson 1 →
- discriminated unionDiscriminated union
- A union of object types that share one field (the tag) with a different literal value in each. Checking the tag narrows the type.Lesson 3 →
- proxy.tsproxy.ts
- The Next.js 16 file that replaces middleware.ts. It runs before a request reaches a route.Lesson 5 →
- satisfiessatisfies
- A TypeScript operator that checks a value against a type but keeps the value's own, more exact type.Lesson 3 →
- Server ActionServer Action
- A function marked to run on the server that a form or button can call. Treat it like a public API endpoint.Lesson 5 →
- Server ComponentServer Component
- A React component that runs only on the server. It can read data directly and sends no JavaScript to the browser.Lesson 5 →
- stacking contextStacking context
- A group of elements that are painted together. A z-index only competes inside its own stacking context. Opacity, transform and filter can create one.Lesson 1 →
- tailwind-mergetailwind-merge
- A small library that removes conflicting Tailwind classes, so the last one wins (for example p-2 and p-4).Lesson 2 →
- use cacheuse cache
- The Next.js 16 directive that opts a function or component into caching.Lesson 5 →
Backend
- backpressureBackpressure
- A slow reader telling a fast writer to wait, so memory does not fill up. Streams do this for you.Lesson 6 →
- event loopEvent loop
- The part of Node.js (and browsers) that picks up finished work and runs its callbacks one at a time.Lesson 6 →
- graceful shutdownGraceful shutdown
- Stopping a server by finishing current requests and closing connections before the process exits.Lesson 6 →
Data
- aggregation pipelineAggregation pipeline
- A MongoDB query made of ordered stages ($match, $group, $lookup…) where each stage feeds the next.Lesson 7 →
- driver adapterDriver adapter
- In Prisma 7, a small package that connects Prisma Client to a database driver such as pg.Lesson 8 →
- event triggerEvent trigger
- A Hasura feature that calls a webhook when a row is inserted, updated or deleted. Delivery is at-least-once.Lesson 9 →
- N+1N+1 problem
- One query to load a list, then one more query for each row. It is slow. Fix it by loading related data together.Lesson 8 →
- ObjectIdObjectId
- MongoDB's default _id: a 12-byte value that includes a timestamp.Lesson 7 →
- remote schemaRemote schema
- Another GraphQL API that Hasura joins into its own, so clients see one schema.Lesson 9 →
- replica setReplica set
- A group of MongoDB servers holding the same data. One is the primary; the others copy it and can take over.Lesson 7 →
- session variablesSession variables
- Values like X-Hasura-User-Id that Hasura reads from the user's token and uses in permission rules.Lesson 9 →
- shadow databaseShadow database
- A temporary database that Prisma Migrate uses to check that your migrations match your schema.Lesson 8 →
- shard keyShard key
- The field MongoDB uses to decide which shard stores a document. A poor key makes one shard too busy.Lesson 7 →
AI
- agent harnessHarness
- The code around a model that runs its loop: calling tools, managing context, permissions and memory. (Not the same as an evaluation harness, which only tests models.)Lesson 10 →
- context windowContext window
- The maximum amount of text (in tokens) a model can look at in one request.Lesson 10 →
- embeddingEmbedding
- A list of numbers that represents the meaning of a text, so similar texts are close together.Lesson 10 →
- hallucinationHallucination
- When a model states something false with confidence.Lesson 10 →
- MCPModel Context Protocol
- An open standard for letting AI applications connect to tools and data through servers.Lesson 10 →
- prompt injectionPrompt injection
- Hidden instructions in untrusted text that try to make a model ignore its rules or misuse its tools.Lesson 10 →
- RAGRetrieval-augmented generation
- Finding relevant documents first, then giving them to the model with the question so the answer uses your data.Lesson 10 →
- streamTextstreamText
- The AI SDK function that calls a model and returns its answer piece by piece as it is produced.Lesson 11 →
- tool callingTool calling
- A model asking your code to run a function with given arguments, then using the result in its answer.Lesson 11 →
Search and analytics
- distinct_iddistinct_id
- The ID Mixpanel uses to say which user an event belongs to.Lesson 12 →
- funnelFunnel
- A report that shows how many users complete each step of a flow, like sign-up, and where they drop off.Lesson 12 →
- tenant tokenTenant token
- A Meilisearch token that carries search rules (like a filter) so each user can only see their own documents.Lesson 12 →
- typo toleranceTypo tolerance
- A search engine finding results even when the query has small spelling mistakes.Lesson 12 →
Libraries
- idempotency keyIdempotency key
- A unique value sent with a request so repeating it does not repeat the action, such as a second payment.Lesson 13 →
- staleTimestaleTime
- In TanStack Query, how long fetched data counts as fresh before it is fetched again.Lesson 13 →
Experience
- STARSTAR method
- Situation, Task, Action, Result: a simple way to structure a story in an interview.Lesson 14 →
Redis and caching
- cache stampedeCache stampede
- Many requests miss the cache at the same moment and all hit the database together.Lesson 18 →
- cache-asideCache-aside
- A pattern where the app checks the cache first, and on a miss reads the database and stores the result in the cache.Lesson 18 →
Queues and webhooks
- dead-letter queueDead-letter queue
- A place where jobs that failed every retry are kept so people can look at them.Lesson 19 →
- outbox patternOutbox pattern
- Saving a message in the same database transaction as your data, then sending it from there later, so nothing is lost.Lesson 19 →
Realtime
- Server-Sent EventsServer-Sent Events (SSE)
- A one-way stream from the server to the browser over normal HTTP.Lesson 20 →
- WebSocketWebSocket
- A long-lived two-way connection between browser and server.Lesson 20 →
Testing
- mockMock
- A fake stand-in for a real part of the system, used in a test.Lesson 21 →
Auth
- OIDCOpenID Connect (OIDC)
- A layer on top of OAuth that tells the app who the user is.Lesson 22 →
- PKCEPKCE
- A small proof added to the OAuth code flow so a stolen code cannot be used by someone else.Lesson 22 →
Payments
- webhook signatureWebhook signature
- A value sent with a webhook that proves the sender is who it claims to be.Lesson 23 →
Git
- monorepoMonorepo
- One repository that holds many apps and packages.Lesson 24 →
- reflogReflog
- Git's private log of where your branches and HEAD pointed, used to recover lost commits.Lesson 24 →
State libraries
- optimistic updateOptimistic update
- Showing the result in the UI right away and undoing it if the server says no.Lesson 25 →
Deploy and monitoring
- SLOService level objective (SLO)
- A target for how reliable a service should be, such as 99.9% of requests succeed.Lesson 26 →
SEO and PostgreSQL
- hreflanghreflang
- A tag that tells search engines which language or region a page is for.Lesson 27 →
- MVCCMVCC
- How PostgreSQL lets readers and writers work together by keeping several versions of a row.Lesson 27 →