# JavaScript glossary: Master level 35 JavaScript terms at the Master 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/master) - [Abstract Syntax Tree](https://www.ask-codey.com/glossary/abstract-syntax-tree): A tree representation of source-code structure used by parsers and tools. - [Accessor Property](https://www.ask-codey.com/glossary/accessor-property): An object property defined by getter and setter functions. - [Call Stack](https://www.ask-codey.com/glossary/call-stack): The stack of function calls currently being executed. - [Comment node](https://www.ask-codey.com/glossary/comment-node): A DOM node containing the text of an HTML comment. - [Data Property](https://www.ask-codey.com/glossary/data-property): An object property that stores a value directly. - [Document node](https://www.ask-codey.com/glossary/document-node): The DOM node representing the whole document and serving as the tree's root. - [Element node](https://www.ask-codey.com/glossary/element-node): A DOM node representing an element and its attributes. - [Enumerability](https://www.ask-codey.com/glossary/enumerability): A property setting that controls whether common enumeration operations include that property. - [Event Loop](https://www.ask-codey.com/glossary/event-loop-javascript): The runtime mechanism that schedules queued work when the call stack is available. - [Execution Context](https://www.ask-codey.com/glossary/execution-context): The runtime state used to execute a script or function call. - [FinalizationRegistry](https://www.ask-codey.com/glossary/finalizationregistry): An advanced API for requesting a callback after an object is garbage-collected. - [Garbage Collection](https://www.ask-codey.com/glossary/garbage-collection-javascript): Automatic recovery of heap memory from objects a program can no longer reach. - [Hidden Class](https://www.ask-codey.com/glossary/hidden-class): An engine optimization that internally groups objects with the same property layout. - [Hoisting](https://www.ask-codey.com/glossary/hoisting): The effect of declarations being registered before execution reaches their source line. - [Inherited Property](https://www.ask-codey.com/glossary/inherited-property): A property found through an object's prototype chain. - [Inline Cache](https://www.ask-codey.com/glossary/inline-cache): An engine optimization that remembers prior property lookup or call results at a code location. - [Just-in-Time Compilation](https://www.ask-codey.com/glossary/just-in-time-compilation-javascript): Runtime compilation of frequently executed JavaScript into optimized machine code. - [Lexical Environment](https://www.ask-codey.com/glossary/lexical-environment): An internal record connecting names in one scope to values and an outer environment. - [Macrotask](https://www.ask-codey.com/glossary/macrotask): An informal name for an event-loop task such as a timer or user event. - [Memory Leak](https://www.ask-codey.com/glossary/memory-leak-javascript): Unwanted memory growth caused by retaining references to objects no longer needed. - [Microtask Queue](https://www.ask-codey.com/glossary/microtask-queue): A high-priority queue used by Promise reactions and queueMicrotask callbacks. - [Node document order](https://www.ask-codey.com/glossary/node-document-order): The order nodes appear when a document tree is traversed from beginning to end. - [Own Property](https://www.ask-codey.com/glossary/own-property): A property defined directly on an object rather than inherited. - [Property Descriptor](https://www.ask-codey.com/glossary/property-descriptor): A record controlling a property's value, accessors, writability, enumerability, and configurability. - [Prototype](https://www.ask-codey.com/glossary/prototype): An object another object consults when a requested property is missing. - [Prototype Chain](https://www.ask-codey.com/glossary/prototype-chain): The linked sequence of prototypes searched during property lookup. - [Proxy Object](https://www.ask-codey.com/glossary/proxy-object): An object that intercepts operations such as reading, writing, and property lookup for another object. - [Realm](https://www.ask-codey.com/glossary/realm): A JavaScript execution environment with its own global object and built-in objects. - [Reflect API](https://www.ask-codey.com/glossary/reflect-api): Built-in methods that perform fundamental object operations and pair naturally with Proxy traps. - [Run-to-Completion](https://www.ask-codey.com/glossary/run-to-completion): The rule that one JavaScript job finishes before another job begins on the same agent. - [Scope Chain](https://www.ask-codey.com/glossary/scope-chain): The sequence of lexical environments searched to resolve a name. - [Task Queue](https://www.ask-codey.com/glossary/task-queue): A queue of callbacks waiting to run as event-loop tasks. - [Temporal Dead Zone](https://www.ask-codey.com/glossary/temporal-dead-zone): The period where a block-scoped variable exists but cannot be accessed before its declaration. - [Text node](https://www.ask-codey.com/glossary/text-node): A DOM node that directly holds a string of characters. - [Weak Reference](https://www.ask-codey.com/glossary/weak-reference-javascript): A reference to an object that does not prevent that object from being garbage-collected. - Previous 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/master