100 Essential JavaScript Definitions for Beginners

100 Essential JavaScript Definitions for Beginners

Basic Concepts

1. JavaScript: A versatile programming language used for creating interactive web pages and applications.

2. Variable: A container for storing data values. Example: let name = "John";

3. Constant: A variable that cannot be reassigned. Example: const PI = 3.14159;

4. Data Type: A classification of data. JavaScript has six primitive data types and one complex data type (Object).

5. String: A sequence of characters enclosed in quotes. Example: "Hello, World!"

6. Number: A numeric data type used for integers and floating-point numbers. Example: 42 or 3.14

7. Boolean: A data type representing true or false values.

8. Undefined: A variable that has been declared but not assigned a value.

9. Null: A deliberate non-value or absence of any object value.

10. Symbol: A unique and immutable primitive data type introduced in ES6.

Operators and Expressions

1. Operator: A symbol that performs operations on values and variables.

2. Assignment Operator (=): Assigns a value to a variable. Example: x = 5;

3. Arithmetic Operators: Perform mathematical operations (+, , , /, %).

4. Comparison Operators: Compare values (==, ===, !=, !==, >, <, >=, <=).

5. Logical Operators: Perform logical operations (&&, ||, !).

6. Ternary Operator: A shorthand for an if-else statement. Example: condition ? expr1 : expr2

7. Expression: A combination of values, variables, and operators that resolves to a value.

Control Flow

1. If Statement: A conditional statement that executes code based on a condition.

2. Else Statement: Specifies code to be executed when the if condition is false.

3. Else If Statement: Checks multiple conditions in sequence.

4. Switch Statement: Selects one of many code blocks to be executed.

5. For Loop: A control flow statement for iterating a specific number of times.

6. While Loop: Executes a block of code as long as a condition is true.

7. Do...While Loop: Similar to while, but always executes the code block at least once.

8. Break Statement: Terminates a loop or switch statement.

9. Continue Statement: Skips the rest of the loop iteration and continues with the next one.

Functions

1. Function: A reusable block of code that performs a specific task.

2. Function Declaration: Defines a named function. Example: function greet() { ... }

3. Function Expression: Assigns a function to a variable. Example: const greet = function() { ... }

4. Arrow Function: A concise way to write function expressions. Example: const greet = () => { ... }

5. Parameters: Variables listed as part of a function definition.

6. Arguments: Values passed to a function when it is called.

7. Return Statement: Specifies the value to be returned by a function.

8. Callback Function: A function passed as an argument to another function.

9. Higher-Order Function: A function that takes other functions as arguments or returns them.

Objects and Arrays

1. Object: A complex data type representing a collection of key-value pairs.

2. Property: A key-value pair in an object.

3. Method: A function that is a property of an object.

4. Array: An ordered collection of elements stored in a single variable.

5. Index: A numeric position of an element in an array (starting from 0).

6. Array Method: Built-in functions to manipulate arrays (e.g., push(), pop(), slice()).

7. Object Literal: A way to create objects using curly braces {}.

8. Dot Notation: Accessing object properties using a dot. Example: person.name

9. Bracket Notation: Accessing object properties using brackets. Example: person["name"]

DOM and Events

1. DOM (Document Object Model): A programming interface for HTML and XML documents.

2. Element: An individual part of an HTML document, like a paragraph or div.

3. Node: Any object in the DOM tree.

4. Event: An action that occurs in the browser, such as a button click or page load.

5. Event Listener: A function that responds to events triggered by the user.

6. Event Handler: A function that runs when an event occurs.

Advanced Concepts

1. Scope: The context in which variables are declared and accessible.

2. Closure: A function that retains access to its outer function's scope.

3. Hoisting: The behavior of moving variable and function declarations to the top of their scope.

4. This Keyword: Refers to the object it belongs to.

5. Prototype: An object from which other objects inherit properties.

6. Inheritance: The ability of an object to acquire properties and methods from another object.

7. Class: A blueprint for creating objects (introduced in ES6).

8. Constructor: A special method for creating and initializing objects created within a class.

9. Asynchronous Programming: Writing code that doesn't run sequentially.

10. Promise: An object representing the eventual completion or failure of an asynchronous operation.

11. Async/Await: A modern syntax for working with asynchronous code using promises.

12. Module: A self-contained piece of code with private and public interfaces.

13. Export: A keyword used to make code in a module accessible to other files.

14. Import: A keyword used to include code from other modules.

15. JSON (JavaScript Object Notation): A lightweight data interchange format.

ES6+ Features

1. Let: A block-scoped variable declaration.

2. Const: A block-scoped declaration for constants.

3. Template Literals: String literals allowing embedded expressions. Example: `Hello, ${name}!`

4. Destructuring: A syntax for extracting values from arrays or properties from objects.

5. Spread Operator: An operator used to spread elements of an array or object. Example: ...array

6. Rest Parameter: Collects multiple elements into an array. Example: function(a, ...rest)

7. Default Parameters: Allows setting default values for function parameters.

8. Map: A data structure that stores key-value pairs.

9. Set: A data structure that stores unique values.

10. Symbol: A unique and immutable primitive data type.

Browser APIs and Web Development

1. AJAX (Asynchronous JavaScript and XML): A technique for making asynchronous requests to the server.

2. Fetch API: A modern replacement for XMLHttpRequest for making HTTP requests.

3. Local Storage: A web storage object for storing data in the browser.

4. Session Storage: Similar to Local Storage but data is cleared when the browser session ends.

5. Cookies: Small pieces of data stored on the client's computer by websites.

6. Geolocation API: Allows web applications to access the user's geographical location.

7. Web Workers: Scripts that run in the background, separate from the main page.

8. Service Workers: Scripts that act as proxy servers between web applications, the browser, and the network.

9. WebSockets: A protocol providing full-duplex communication channels over a single TCP connection.

10. Canvas API: Allows dynamic, scriptable rendering of 2D shapes and images.

Development Tools and Practices

1. Debugging: The process of finding and fixing errors in code.

2. Console.log(): A method to output messages to the browser console for debugging.

3. Linter: A tool that analyzes code for potential errors and style issues.

4. Transpiler: A tool that converts code from one version of JavaScript to another.

5. Bundler: A tool that combines multiple JavaScript files into a single file.

6. npm (Node Package Manager): A package manager for JavaScript libraries and tools.

7. Version Control: A system for tracking and managing changes to code.

8. Git: A popular distributed version control system.

9. Unit Testing: Testing individual units or components of a program.

10. Integration Testing: Testing how different parts of an application work together.

11. Continuous Integration (CI): The practice of automating the integration of code changes.

12. Deployment: The process of making a website or application available on the internet.

13. Minification: The process of removing unnecessary characters from code without changing functionality.

14. Code Splitting: Dividing code into smaller chunks to improve performance.

15. Progressive Enhancement: A strategy for web design that emphasizes core webpage content first.

Conclusion