JavaScript Glossary Last Updated : 23 Jul, 2025 Comments Improve Suggest changes 16 Likes Like Report JavaScript is one of the most widely used programming languages for web development. This glossary concisely explains key JavaScript terms and concepts, making it easier to understand and reference them.Arrays: Used to store multiple values in a single variable. They are zero-indexed and can hold mixed data types.Async/Await: Async/Await are way to handle asynchronous operations in JavaScript, built on Promises. Arrow Functions: Arrow functions in JavaScript are a concise syntax for writing functions introduced in ES6. ArrayBuffer: ArrayBuffer in JavaScript is a fixed-length binary data buffer used to handle raw binary data.Axios: Axios is a popular JavaScript library for making HTTP requests.Boolean: Boolean represents one of two values: true or false, often used for logical operations and conditional statements.Browser Object Model (BOM): It provides APIs to interact with the browser's features, such as managing the browser window.Bind (Function Method): The bind() Creates a new function with this bound to a specific object.BigInt: A BigInt is a data type for representing integers larger than a Number. MAX_SAFE_INTEGER.Break Statement: A Break Statement terminates a loop or switch statement.Callback Functions: A Callback function is a function passed as an argument to another function, to be executed at a later time. Classes: Class is a blueprint for creating objects with methods and properties.Closures: A Closure is a function that remembers its lexical scope even when executed outside of it.Conditional Statements: A Conditional Statement is a Control flow statement for decision-making.Const (Declaration): The const declaration in JavaScript is used to declare variables whose values cannot be reassigned after initialization.Currying: It is a functional programming technique where a function takes multiple arguments one at a time, returning a new function for each argument.DOM (Document Object Model): A programming interface for HTML and XML documents.Destructuring: Destructuring is a syntax in JavaScript that allows unpacking values from arrays or objects into distinct variables.Default Parameters: Allows default values for function parameters if none are provided.Data Types: Categories of values in JavaScript (e.g., number, string, object).Date: Provides methods to work with dates and times.Debugging: The process of finding and fixing errors in code.Defer (Script Attribute): Ensures scripts execute after the HTML is parsed.Deep Copy: Creates a completely independent copy of an object or array.Events: Actions or occurrences detected by JavaScript, such as user interactions or browser triggers.Error Handling: Mechanisms for catching and managing runtime errors.ECMAScript (ES): EcmaScript is the standard for JavaScript, with various editions introducing new features.Event Loop: Event Loop Handles asynchronous operations in JavaScript.Expressions: Expressions are the Code snippets that produce a value.Encapsulation (OOP): Encapsulation hides the internal state of an object and allows controlled access.Functions: Functions are reusable blocks of code designed to perform a specific task.For Loop: A control flow statement for iterating over a block of code a fixed number of times.Fetch API: Fetch API provides a modern way to make HTTP requests.ForEach: ForEach iterates over elements of an array, executing a function for each element.Filter: Filter method creates a new array with elements that pass a specified condition.Generators: Generator function are the functions that can be paused and resumed, producing a sequence of values.Getters: Getters are the special methods that retrieve the value of an object property.Global Scope: Variables declared outside any function or block, accessible anywhere in the code are global scoped.Garbage Collection: Garbage Collection is the automatic memory management in JavaScript, where unused memory is reclaimed. Higher-Order Functions: Higher Order Function are the functions that take other functions as arguments or return functionsHoisting: JavaScript's behavior of moving declarations to the top of their scope before execution called Hoisting.HTTP Requests: HTTP requests are used to communicate with servers over the HTTP protocol.Iterators: Iterators are the objects that allow traversal over a collection, one element at a time. If-Else Statements: If-Else Statements are the conditional structure for executing code based on a condition.IIFE (Immediately Invoked Function Expressions): Functions that execute immediately after being defined are called IIFE.IndexOf: IndexOf finds the first occurrence of a value in a string or array.Inheritance (OOP): Inheritance are the mechanism to create a new class based on an existing class.JSON (JavaScript Object Notation): JSON is a lightweight data-interchange format that's easy to read and write for humans and machines.JS Modules: Modules are the way to structure and share code across different files using export and import.JavaScript Objects: JavaScript Objects are the collection of key-value pairs, where keys are strings and values can be any data type.Loops: Control structures that allow repetitive execution of a block of code.Let keyword: Let keyword used to declare variables with block scope.Logical Operators: Operators used to perform logical operations, typically with boolean values.Math Object: Math Object are the built-in object that provides mathematical constants and functions.map(): Map() creates a new array by applying a function to each element of an existing array.null: It is a special JavaScript value representing the intentional absence of any object value.NaN (Not-a-Number): NaN is aspecial JavaScript value representing an invalid number or a mathematical operation that cannot be performed.Object-Oriented Programming (OOP): OOP is a programming paradigm based on the concept of objects, using classes and inheritance.Operators: Operators are the symbols used to perform operations on values and variables.Primitive Data Types: Primitive Data Types are the simplest types in JavaScript, such as string, number, boolean, null, undefined, symbol, and bigint.Promises: A JavaScript Promise is an object that represents the eventual completion (or failure) of an asynchronous operation and its resulting value.Rest Operator (...): Rest Operator collects remaining elements into an array or object.Scope: Scope determines the accessibility of variables, functions, and objects in different parts of code.Strings: Strings are the sequence of characters used to represent text.setTimeout(): Executes a function after a specified delay.Shallow Copy: Shallow copy is the copy of an object/array where only the first level is copied.Switch Statement: A control flow statement for executing one block of code out of many.Ternary Operator: Ternary operator is the shorthand for if-else statements.Template Literals: Template literals allow embedding expressions and multi-line strings using ${expression} syntax.this Keyword: this keyword refers to the object that is executing the current functionTry-Catch: A block to handle exceptions in code.Undefined: A variable that has been declared but not assigned a value is called undefined.Unary Operators: Unary Operators are operators that operate on a single operand.Variables: Variables are the containers for storing data values in JavaScript.window Object: The window object is the global object representing the browser window in which the script is running.WeakMap: A WeakMap is a collection of key-value pairs where the keys are objects, and the values can be any arbitrary value.WeakSet: A WeakSet is a collection of unique objects where the values are weakly held (can be garbage collected). Create Quiz Comment S sneha2dmo Follow 16 Improve S sneha2dmo Follow 16 Improve Article Tags : JavaScript Web Technologies javascript-basics JavaScript-Misc Explore JavaScript BasicsIntroduction to JavaScript4 min readVariables and Datatypes in JavaScript6 min readJavaScript Operators5 min readControl Statements in JavaScript4 min readArray & StringJavaScript Arrays7 min readJavaScript Array Methods7 min readJavaScript Strings5 min readJavaScript String Methods9 min readFunction & ObjectFunctions in JavaScript5 min readJavaScript Function Expression3 min readFunction Overloading in JavaScript4 min readObjects in JavaScript4 min readJavaScript Object Constructors4 min readOOPObject Oriented Programming in JavaScript3 min readClasses and Objects in JavaScript4 min readWhat Are Access Modifiers In JavaScript ?5 min readJavaScript Constructor Method7 min readAsynchronous JavaScriptAsynchronous JavaScript2 min readJavaScript Callbacks4 min readJavaScript Promise4 min readEvent Loop in JavaScript4 min readAsync and Await in JavaScript2 min readException HandlingJavascript Error and Exceptional Handling6 min readJavaScript Errors Throw and Try to Catch2 min readHow to create custom errors in JavaScript ?2 min readJavaScript TypeError - Invalid Array.prototype.sort argument1 min readDOMHTML DOM (Document Object Model)8 min readHow to select DOM Elements in JavaScript ?3 min readJavaScript Custom Events4 min readJavaScript addEventListener() with Examples9 min readAdvanced TopicsClosure in JavaScript4 min readJavaScript Hoisting6 min readScope of Variables in JavaScript3 min readJavaScript Higher Order Functions7 min readDebugging in JavaScript4 min read Like