Introduction to JavaScript: 100 Commonly Used Terms
JavaScript is a versatile and powerful programming language used primarily for creating interactive and dynamic content on websites. Mastering JavaScript involves understanding various terms and concepts that are fundamental to its use. This guide will introduce you to 100 commonly used JavaScript words, providing explanations and clickable hyperlinks for further reading.
1. Array
Explanation: A collection of items stored at contiguous memory locations. Arrays can hold multiple values under a single name. Learn more.
2. Boolean
Explanation: A data type that can be either true or false. It is often used in conditional statements. Learn more.
3. Callback
Explanation: A function passed into another function as an argument, which is then invoked inside the outer function. Learn more.
4. Class
Explanation: A blueprint for creating objects with shared properties and methods. Learn more.
5. Constructor
Explanation: A special method for creating and initializing objects created within a class. Learn more.
6. DOM (Document Object Model)
Explanation: A programming interface for web documents, allowing scripts to update the content, structure, and style of a document. Learn more.
7. Event
Explanation: An action or occurrence recognized by software, often triggered by user interaction. Learn more.
8. Function
Explanation: A block of code designed to perform a particular task, defined once but can be executed multiple times. Learn more.
9. Object
Explanation: A collection of properties, where each property is a key-value pair. Learn more.
10. Promise
Explanation: An object representing the eventual completion or failure of an asynchronous operation. Learn more.
11. Prototype
Explanation: An object from which other objects inherit properties. Learn more.
12. Variable
Explanation: A named container used to store data values. Learn more.
13. String
Explanation: A sequence of characters used to represent text. Learn more.
14. Number
Explanation: A numeric data type representing both integer and floating-point values. Learn more.
15. Array.prototype.map()
Explanation: A method that creates a new array with the results of calling a provided function on every element in the calling array. Learn more.
16. Event Listener
Explanation: A procedure in JavaScript that waits for a specific event to occur on an element. Learn more.
17. AJAX (Asynchronous JavaScript and XML)
Explanation: A technique for creating interactive web applications that allow for asynchronous data loading. Learn more.
18. JSON (JavaScript Object Notation)
Explanation: A lightweight data interchange format that is easy for humans to read and write, and easy for machines to parse and generate. Learn more.
19. API (Application Programming Interface)
Explanation: A set of rules and protocols for building and interacting with software applications. Learn more.
20. Callback Hell
Explanation: A situation where callbacks are nested within callbacks, leading to code that is hard to read and maintain. Learn more.
21. Closure
Explanation: A function that retains access to its lexical scope, even when the function is executed outside that scope. Learn more.
22. Destructuring
Explanation: A syntax that allows unpacking values from arrays or properties from objects into distinct variables. Learn more.
23. ES6 (ECMAScript 2015)
Explanation: The sixth edition of the ECMAScript standard, introducing many new features to JavaScript. Learn more.
24. Hoisting
Explanation: JavaScript’s behavior of moving declarations to the top of their scope before execution. Learn more.
25. IIFE (Immediately Invoked Function Expression)
Explanation: A function expression that is executed immediately after its creation. Learn more.
26. Map
Explanation: A collection of key-value pairs where keys are unique. Learn more.
27. Module
Explanation: A self-contained unit of code that can be imported and exported between files. Learn more.
28. Null
Explanation: A special value representing the absence of any object value. Learn more.
29. Scope
Explanation: The context in which variables and functions are accessible. Learn more.
30. Strict Mode
Explanation: A way to opt into a restricted variant of JavaScript, which can catch common coding mistakes. Learn more.
31. Symbol
Explanation: A unique and immutable primitive value used as the key for object properties. Learn more.
32. Template Literal
Explanation: A feature in ES6 that allows for easier string interpolation and multi-line strings. Learn more.
33. Try…Catch
Explanation: A statement used to handle exceptions that occur in a block of code. Learn more.
34. Undefined
Explanation: A data type that represents a variable that has not been assigned a value. Learn more.
35. Var
Explanation: A keyword used to declare variables in JavaScript. Learn more.
36. Let
Explanation: A keyword used to declare block-scoped variables. Learn more.
37. Const
Explanation: A keyword used to declare variables whose values cannot be reassigned. Learn more.
38. While Loop
Explanation: A control structure that executes a block of code as long as its condition evaluates to true. Learn more.
39. For Loop
Explanation: A control structure that iterates a block of code a specific number of times. Learn more.
40. Break
Explanation: A statement that exits from the current loop or switch statement. Learn more.
41. Continue
Explanation: A statement that skips the current iteration of a loop and proceeds to the next iteration. Learn more.
42. Switch
Explanation: A control statement that allows the execution of code based on different cases. Learn more.
43. This
Explanation: A keyword that refers to the current object in a method or function. Learn more.
44. Set
Explanation: A collection of unique values, where each value can only occur once. Learn more.
45. WeakMap
Explanation: A collection of key-value pairs where keys are objects and values can be any value. Learn more.
46. WeakSet
Explanation: A collection of objects where each object can only occur once. Learn more.
47. Event Bubbling
Explanation: A method of event propagation where events are first captured by the innermost element and then propagated to outer elements. Learn more.
48. Event Delegation
Explanation: A technique for handling events efficiently by using a single event listener to manage events for multiple elements. Learn more.
49. Fetch API
Explanation: A modern way to make HTTP requests in JavaScript. Learn more.
50. Async/Await
Explanation: Syntax for writing asynchronous code that looks synchronous, making it easier to manage asynchronous operations. Learn more.
51. Arrow Function
Explanation: A concise way to write functions using the => syntax, often with a simpler syntax for anonymous functions. Learn more.
52. Binding
Explanation: The process of associating an object with a function, such that this refers to the object. Learn more.
53. Call Stack
Explanation: A stack data structure that stores information about the active subroutines of a computer program. Learn more.
54. Event Loop
Explanation: A mechanism that handles asynchronous operations by continuously checking the call stack and task queue. Learn more.
55. Generator Function
Explanation: A special type of function that can be paused and resumed, using yield to return intermediate results. Learn more.
56. Iterator
Explanation: An object that defines a sequence and potentially a return value upon completion. Learn more.
57. Map Method
Explanation: A method that creates a new array with the results of calling a provided function on every element in the array. Learn more.
58. Reduce Method
Explanation: A method that executes a reducer function on each element of the array, resulting in a single output value. Learn more.
59. SetTimeout
Explanation: A function that sets a timer to execute a function or specified piece of code once the timer expires. Learn more.
60. SetInterval
Explanation: A function that repeatedly calls a function or executes a code snippet with a fixed time delay between each call. Learn more.
61. Symbol.iterator
Explanation: A method that returns the default iterator for an object. Learn more.
62. Typeof
Explanation: An operator that returns a string indicating the type of the unevaluated operand. Learn more.
63. Void
Explanation: An operator that evaluates an expression and returns undefined. Learn more.
64. With Statement
Explanation: A statement used to extend the scope chain for a statement. Learn more.
65. WeakRef
Explanation: A weak reference to an object that does not prevent garbage collection. Learn more.
66. Iterator Protocol
Explanation: The rules that an object must follow to be considered an iterator, including the next method. Learn more.
67. For-Of Loop
Explanation: A loop that iterates over iterable objects such as arrays and strings. Learn more.
68. Reflect
Explanation: A built-in object that provides methods for interceptable JavaScript operations. Learn more.
69. WeakMap
Explanation: A collection of key-value pairs where keys are objects and values can be any value, with weak references to keys. Learn more.
70. WeakSet
Explanation: A collection of objects where each object can only occur once, and the references to objects are weak. Learn more.
71. Async Function
Explanation: A function that allows for asynchronous operations to be performed using await within its body. Learn more.
72. Await
Explanation: An operator that waits for a promise to resolve and returns the resolved value. Learn more.
73. Try…Finally
Explanation: A combination of try and finally blocks where the finally block executes regardless of whether an error was thrown. Learn more.
74. Document
Explanation: An object that represents the content of a web page, providing methods to manipulate the HTML. Learn more.
75. Window
Explanation: An object representing the browser window, providing methods and properties for interacting with the browser environment. Learn more.
76. History
Explanation: An object that provides access to the browser’s history, allowing navigation through previous pages. Learn more.
77. LocalStorage
Explanation: A web storage API that provides storage that persists even after the browser is closed. Learn more.
78. SessionStorage
Explanation: A web storage API that provides storage for the duration of the page session, lasting until the browser or tab is closed. Learn more.
79. WebSocket
Explanation: A protocol that provides full-duplex communication channels over a single TCP connection. Learn more.
80. Geolocation
Explanation: An API that provides web applications with the ability to access the geographical location of a user’s device. Learn more.
81. Intersection Observer
Explanation: An API that allows for efficient observation of the visibility of elements within a container. Learn more.
82. Service Worker
Explanation: A script that runs in the background and is used to handle network requests, cache resources, and manage offline capabilities. Learn more.
83. Push API
Explanation: An API that allows web applications to receive push notifications from a server. Learn more.
84. Cache API
Explanation: An API that allows for storing and retrieving resources from the cache, providing offline access to web resources. Learn more.
85. WebAssembly
Explanation: A binary instruction format for a stack-based virtual machine that enables high-performance applications on web pages. Learn more.
86. Media Queries
Explanation: A feature of CSS used to apply styles based on the characteristics of the viewport, such as its width or resolution. Learn more.
87. Template Literals
Explanation: A feature that allows for embedded expressions and multi-line strings using backticks. Learn more.
88. Destructuring Assignment
Explanation: A syntax that allows unpacking values from arrays or properties from objects into distinct variables. Learn more.
89. Rest Parameter
Explanation: A syntax that allows a function to accept an indefinite number of arguments as an array. Learn more.
90. Spread Operator
Explanation: A syntax that allows an array or object to be expanded into individual elements or properties. Learn more.
91. Dynamic Typing
Explanation: A feature of JavaScript where variables can hold values of any type, and their types are determined at runtime. Learn more.
92. Prototype Inheritance
Explanation: A feature that allows objects to inherit properties and methods from other objects. Learn more.
93. Object Literal
Explanation: A notation for defining objects using a set of key-value pairs enclosed in curly braces. Learn more.
94. Constructor
Explanation: A special method for creating and initializing objects in a class. Learn more.
95. Class
Explanation: A blueprint for creating objects with shared properties and methods. Learn more.
96. Inheritance
Explanation: A mechanism where one class inherits properties and methods from another class. Learn more.
97. Encapsulation
Explanation: The concept of bundling data and methods that operate on that data within a single unit or class. Learn more.
98. Polymorphism
Explanation: A concept where a single function or method can operate in different ways depending on its input. Learn more.
99. Closure
Explanation: A feature where a function retains access to its lexical scope even when the function is executed outside that scope. Learn more.
100. Event Target
Explanation: An interface that allows for event handling and dispatching events. Learn more.