SMALL DEFINITIONS. FEWER DETOURS.

The words, unpacked.

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125 terms

accessibility
the practice of making a page usable by people who perceive, operate, or understand it in different ways.
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API
an agreed interface that lets one piece of software use another’s capabilities.
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argument
the actual value you pass into a function when you call it.
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array
an ordered JavaScript collection whose items are accessed by positions starting at zero.
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asynchronous
code that can start a task and keep going without waiting for it to finish, coming back to handle the result later.
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authentication
the check that decides who the caller is.
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authorization
the check that decides whether this caller may do this action.
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binding
the connection between a name and the value that name currently refers to.
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BOLA
an API that checks the caller is logged in and then returns whatever id they asked for.
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box model
the content, padding, border, and margin the browser wraps around every element.
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branch
a movable name that points at one commit.
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callback
a function you hand to another function to be run when needed, immediately or later.
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cascade
the ordered process that decides which CSS declaration wins when several apply to one element.
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closure
a function together with access to the surrounding bindings where it was created.
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code review
a deliberate check of a change for correctness, edge cases, and intent before it is trusted.
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collection
a named group of MongoDB documents.
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commit
a snapshot of files plus pointers to its parent commits.
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component
a function that returns the UI for one piece of the interface, given its props.
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controlled component
a form field whose displayed value comes from React state on every render.
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CORS
the browser’s system for checking whether a server allows a page from another origin to read its response.
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CRUD
create, read, update, and delete: the four everyday operations on stored records.
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CSRF
a cross-site request that rides the victim's cookies without their intent.
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debounce
wait until events go quiet for a chosen delay before running the latest requested work.
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document
one MongoDB record, shaped like an object with its own fields.
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DOM
the browser’s live tree of nodes representing the current document.
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edge case
an input or situation at the boundary of a contract where a happy-path solution often fails.
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embedding
storing related values inside the same document as the parent.
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endpoint
one method and path a server is willing to answer.
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event delegation
handling descendant interactions with a listener on a shared ancestor.
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execution context
the environment JavaScript sets up to run a piece of code, tracking that moment's variables, scope, and `this`.
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expression
a piece of code that produces a value (like `2 + 2`).
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flexbox
a one-dimensional CSS layout mode that lines items up in a row or a column and distributes free space.
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function
a reusable block of code that performs a task, optionally taking inputs and producing an output.
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grid
a two-dimensional CSS layout mode that places items into rows and columns at the same time.
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hallucination
a fluent model answer that is wrong, invented, or unsupported by the facts you need.
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hashing
turning a password into a verifier you cannot reverse.
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HEAD
the marker for the commit you currently have checked out.
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hoisting
JavaScript's behavior of processing certain declarations before running the rest of the code, which is why some variables/functions seem usable before the line they're written on.
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hook
a function whose name starts with use and that lets a component remember state or subscribe to something.
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HTTP
the request-and-response protocol browsers and servers use to exchange web resources.
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idempotency
repeating the same request does not create a second effect.
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identity
whether two references point to the very same object.
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immutable
cannot be changed after it's created; any "change" actually produces a brand new value instead.
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index
a structure that lets a query find matching documents without reading the whole collection.
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instance
one specific object created from a class or constructor — like one filled-out copy of a blank form.
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iterable
a value that can supply an iterator for reading its values in sequence.
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iteration
going through a collection of items one at a time, usually with a loop.
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JSON
a text format for exchanging structured data such as objects, arrays, strings, and numbers.
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JWT
a signed header and payload a verifier can check without a session row.
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lexical scope
name lookup determined by where code is written, rather than by where a function is called.
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media query
a CSS condition, often about viewport width, that applies rules only while that condition is true.
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memoization
caching a result so the same inputs can skip repeating the work.
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merge
joining two lines of history, sometimes with a commit that has two parents.
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merge conflict
overlapping edits that Git will not guess between.
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method
a function that belongs to an object, called using dot notation.
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middleware
a function that runs between the request arriving and the response being sent.
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middleware chain
the ordered functions that see a request before the route handler does.
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module
a file or unit of code with private names and an explicit public interface for other code.
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multi-factor authentication
MFA, a second check beyond the password, sometimes asked only when the request looks riskier.
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mutable
able to be changed after it's created, without creating a brand new thing.
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NaN
a special numeric value representing a calculation or conversion that did not produce a valid number.
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null
a value that deliberately represents "nothing" or "empty," set on purpose by the programmer.
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nullish
a value that is either null or undefined.
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OAuth
a way for a user to grant your app access without giving you their password.
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object
a collection of related data and behavior, stored as named key-value pairs.
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observability
being able to tell what a failed request did from its trace and its log fields.
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origin
the conventional name for the remote you cloned or plan to push to.
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package
a published folder of code, named by a package.json file.
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pagination
returning one slice of a list, plus enough information to ask for the next slice.
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parameter
the placeholder name a function uses in its own definition for a value it expects to receive.
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passkey
a WebAuthn key pair the browser will use only for the origin it was created for.
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PKCE
a proof that the client redeeming an authorization code is the one that started the login.
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primitive
one of JavaScript's basic, simple values (string, number, boolean, etc.) that isn't made up of other values.
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promise
an object representing one eventual fulfilled result or rejected failure.
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prompt
the instructions, context, and constraints you give a model so it can attempt a useful answer.
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prop
an input a parent passes into a component, read on that render and not changed by the child.
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property
a named piece of data stored on an object.
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prototype
another object that JavaScript consults when a property is missing on the current object.
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pull request
a proposed set of commits plus the conversation about merging them.
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pure function
a function that returns the same result for the same inputs and does not cause observable side effects.
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query
the filter that selects which documents an operation should see.
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rate limiting
refusing further calls after a caller passes a count or a budget you set.
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RBAC
authorization that allows an action when the caller's role includes it.
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rebase
replaying commits onto a new base, which writes new commit hashes.
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receiver
the object supplied as this for a particular regular function call.
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reconciliation
React’s process of matching the previous element tree to the next one so it can update the DOM.
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recursion
a function solving a problem by calling itself on a smaller or simpler case.
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reference type
a value like an object or array that's stored as a pointer to somewhere in memory, so copying the variable copies the pointer, not the whole value.
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referencing
storing an id that points at a document in another collection.
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refresh token
a longer-lived credential used to mint a new short-lived access token.
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remote
another repository this one knows by a short name.
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render
one call of a component function that produces the elements React will reconcile.
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repository
the stored history of snapshots for one project, plus the labels that point into it.
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request
the method, path, and optional body a client sends to a server.
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response
the status and body a server sends back for one request.
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responsive design
building one layout that stays usable as the viewport and the content change size.
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root cause
the underlying condition that produces a symptom, not merely the symptom itself.
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route
the method, path pattern, and function that answer one request.
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salt
a unique value stored beside a password hash so identical passwords differ.
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scope
the area of your code where a particular variable is visible and usable.
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semantic element
an HTML element whose name describes the role of the content, not only how it looks.
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server
a process that waits for a request and writes a response.
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session
server-side state looked up by an id the browser sends back.
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short-circuit evaluation
skipping the rest of an expression once its result is already determined.
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side effect
an observable change beyond simply returning a value from a calculation.
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specificity
the cascade weight of a selector, used when two declarations target the same property.
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staging area
the index: the snapshot that the next commit will store.
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state
the information a program keeps that can affect what happens next.
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statement
a complete instruction that performs an action, like declaring a variable or running a loop.
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streaming response
a body that arrives as a sequence of chunks or events instead of one JSON value.
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strict mode
a JavaScript mode that turns some silent mistakes into errors and changes a few unsafe defaults.
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subscription
a registration asking a source to notify your code when future events or values arrive.
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synchronous
code that runs one line at a time, in order, each line waiting for the one before it to finish.
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syntax
the exact rules for how code must be written so the computer can understand it, like grammar rules for a language.
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temporal dead zone
the period when a let or const binding exists in its scope but cannot yet be read.
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thread
one sequence of instructions that can execute work.
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throttle
limit how often work runs while repeated events keep arriving.
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truthy and falsy
how JavaScript treats a value when a boolean decision is required.
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type coercion
JavaScript automatically converting a value from one type to another so an operation can complete.
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undefined
the value JavaScript automatically gives to something that's been declared but not yet assigned.
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variable
a named container that holds a value you can use and change later.
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viewport
the visible area of the page, which the viewport meta element and media queries both refer to.
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virtual DOM
the element tree React keeps in memory and compares before changing the real DOM.
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working directory
the files you are editing right now, before they are staged.
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XSS
attacker-controlled markup that the browser runs as your origin.
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accessibility

API

argument

array

asynchronous

authentication

authorization

binding

BOLA

box model

branch

callback

cascade

closure

code review

collection

commit

component

controlled component

CORS

CRUD

CSRF

debounce

document

DOM

edge case

embedding

endpoint

event delegation

execution context

expression

flexbox

function

grid

hallucination

hashing

HEAD

hoisting

hook

HTTP

idempotency

identity

immutable

index

instance

iterable

iteration

JSON

JWT

lexical scope

media query

memoization

merge

merge conflict

method

middleware

middleware chain

module

multi-factor authentication

mutable

NaN

null

nullish

OAuth

object

observability

origin

package

pagination

parameter

passkey

PKCE

primitive

promise

prompt

prop

property

prototype

pull request

pure function