# JavaScript glossary: Journeyman level

62 JavaScript terms at the Journeyman level, each with a short definition and a link to its full page.

Updated: October 16, 2026

[Study these as flash cards](https://www.ask-codey.com/decks/javascript/journeyman)

- [.catch()](https://www.ask-codey.com/glossary/catch): A Promise method that schedules error handling for rejection.
- [.then()](https://www.ask-codey.com/glossary/then): A Promise method that schedules work for successful completion.
- [Array Iterator Method](https://www.ask-codey.com/glossary/array-iterator-method): An Array method that processes items through a callback, such as map, filter, or find.
- [async](https://www.ask-codey.com/glossary/async): A keyword added to functions that allows fetching data in parallel.
- [async Function](https://www.ask-codey.com/glossary/async-function): A function that always returns a Promise and allows await in its body.
- [await](https://www.ask-codey.com/glossary/await): An operator that pauses an async function until a value or Promise settles.
- [catch Block](https://www.ask-codey.com/glossary/catch-block-javascript): A block that handles a matching exception from its try block.
- [Class](https://www.ask-codey.com/glossary/class-javascript): A blueprint for making objects that bundle data with actions.
- [Class Method](https://www.ask-codey.com/glossary/class-method): A function defined as a member of a JavaScript class.
- [Closure](https://www.ask-codey.com/glossary/closure-javascript): An inner function that remembers the variables around it.
- [Constructor](https://www.ask-codey.com/glossary/constructor-javascript): The special class method that initializes a newly created JavaScript object.
- [Custom Error](https://www.ask-codey.com/glossary/custom-error): An application-specific error class extending JavaScript's Error class.
- [Default Export](https://www.ask-codey.com/glossary/default-export): The single value a module marks as its default export.
- [defer](https://www.ask-codey.com/glossary/defer): A Boolean classic-script attribute that delays execution until parsing finishes while preserving document order.
- [Dependency](https://www.ask-codey.com/glossary/dependency-javascript): External code that a project needs to compile or run.
- [Development Dependency](https://www.ask-codey.com/glossary/development-dependency): A package needed for development or testing but not for the application at runtime.
- [DOM](https://www.ask-codey.com/glossary/dom): The browser's object representation of an HTML document.
- [Encapsulation](https://www.ask-codey.com/glossary/encapsulation-javascript): Keeping an object's data behind its methods so it's changed the safe way.
- [Error](https://www.ask-codey.com/glossary/error): An object describing a problem that interrupted normal execution.
- [ES Module](https://www.ask-codey.com/glossary/es-module): A JavaScript file using import and export to declare dependencies and public values.
- [Event](https://www.ask-codey.com/glossary/event-javascript-2): A member that lets an object notify subscribed code that something happened.
- [Event Listener](https://www.ask-codey.com/glossary/event-listener): A callback registered to run when a particular event occurs.
- [every()](https://www.ask-codey.com/glossary/every): An Array method that reports whether every item passes a test.
- [extends](https://www.ask-codey.com/glossary/extends): A keyword that makes one class inherit from another.
- [External script](https://www.ask-codey.com/glossary/external-script): A script loaded from a separate resource through a script element's src attribute.
- [Fetch API](https://www.ask-codey.com/glossary/fetch-api): A browser and runtime API for making HTTP requests that returns a Promise.
- [filter()](https://www.ask-codey.com/glossary/filter-javascript): Keeps only the items that pass a test.
- [finally Block](https://www.ask-codey.com/glossary/finally-block-javascript): A block that normally runs after try and catch whether an exception occurred or not.
- [find()](https://www.ask-codey.com/glossary/find): An Array method that returns the first item satisfying a test.
- [Getter](https://www.ask-codey.com/glossary/getter-javascript): A method that returns an object's stored value.
- [Higher-Order Function](https://www.ask-codey.com/glossary/higher-order-function-javascript): A function that takes or returns another function.
- [Inheritance](https://www.ask-codey.com/glossary/inheritance-javascript): A new class starts with everything from another class, then adds or changes things.
- [Inline script](https://www.ask-codey.com/glossary/inline-script): Script code written directly inside a script element.
- [Instance](https://www.ask-codey.com/glossary/instance-javascript): One object made from a class, with its own data.
- [JSON.parse()](https://www.ask-codey.com/glossary/json-parse): A method that converts valid JSON text into a JavaScript value.
- [JSON.stringify()](https://www.ask-codey.com/glossary/json-stringify): A method that converts a supported JavaScript value into JSON text.
- [Lexical Scope](https://www.ask-codey.com/glossary/lexical-scope): The rule that a function can use names from where it was written.
- [map()](https://www.ask-codey.com/glossary/map-javascript): An Array method that creates a new array by transforming every item.
- [Method Overriding](https://www.ask-codey.com/glossary/method-overriding-javascript): A child class writing its own version of an inherited method.
- [Module script](https://www.ask-codey.com/glossary/module-script): A script processed as a JavaScript module with imports, strict mode, and module scoping.
- [Named Export](https://www.ask-codey.com/glossary/named-export): An exported value imported by its declared export name.
- [npm](https://www.ask-codey.com/glossary/npm): The package registry and command-line client commonly used by JavaScript projects.
- [Package](https://www.ask-codey.com/glossary/package-javascript): A folder of related modules you can import from.
- [package.json](https://www.ask-codey.com/glossary/package-json): A project file containing package metadata, scripts, dependencies, and configuration.
- [Polymorphism](https://www.ask-codey.com/glossary/polymorphism-javascript): Different objects answering the same method call in their own way.
- [Private Field](https://www.ask-codey.com/glossary/private-field): A class field beginning with # that is accessible only inside its declaring class.
- [Promise](https://www.ask-codey.com/glossary/promise): An object representing the eventual fulfillment or rejection of an asynchronous operation.
- [Promise State](https://www.ask-codey.com/glossary/promise-state): A Promise's current state: pending, fulfilled, or rejected.
- [Pure Function](https://www.ask-codey.com/glossary/pure-function): A function that produces the same result for the same inputs without changing outside state.
- [querySelector()](https://www.ask-codey.com/glossary/queryselector): A DOM method that returns the first element matching a CSS selector.
- [Recursion](https://www.ask-codey.com/glossary/recursion-javascript): A function calling itself to solve a smaller piece of the same problem.
- [reduce()](https://www.ask-codey.com/glossary/reduce-javascript): A stream operation that combines elements into one result.
- [Response Object](https://www.ask-codey.com/glossary/response-object): An object returned by fetch containing an HTTP response's status, headers, and body methods.
- [Semantic Versioning](https://www.ask-codey.com/glossary/semantic-versioning): A major.minor.patch numbering convention communicating compatibility and change size.
- [Setter](https://www.ask-codey.com/glossary/setter-javascript): A method that validates or changes an object's stored value.
- [some()](https://www.ask-codey.com/glossary/some): An Array method that reports whether at least one item passes a test.
- [sort()](https://www.ask-codey.com/glossary/sort-javascript): Puts a list in order, changing the list itself.
- [Static Import](https://www.ask-codey.com/glossary/static-import): An import declaration resolved and loaded as part of a module's dependency graph.
- [Static Method](https://www.ask-codey.com/glossary/static-method): A class method called on the class itself rather than an instance.
- [super](https://www.ask-codey.com/glossary/super-javascript): A reference used to access a superclass constructor or member.
- [throw](https://www.ask-codey.com/glossary/throw-javascript): A statement that deliberately raises an exception object.
- [try Block](https://www.ask-codey.com/glossary/try-block-javascript): A block containing code that may throw an exception.

- Previous level: [Apprentice](https://www.ask-codey.com/glossary/subjects/javascript/apprentice)
- Next level: [Freelancer](https://www.ask-codey.com/glossary/subjects/javascript/freelancer)

[Every JavaScript term, by level](https://www.ask-codey.com/glossary/subjects/javascript)

Source: https://www.ask-codey.com/glossary/subjects/javascript/journeyman