JavaScript Fundamentals and Programming Overview

JavaScript: Interpreted or Compiled?

• JavaScript is an interpreted language, not a compiled language.
• Interpreted languages execute code line by line, while compiled languages translate the entire code into machine language before execution.

RAM: Definition and Purpose

• RAM stands for Random Access Memory.
• It's the primary memory of a computer, used for temporary storage of data and instructions that the CPU is currently using.

JavaScript Variable Declarations

• The keywords used to declare variables in JavaScript are:
  • var
  • let
  • const

JavaScript Key Features and Descriptions

• Functions: Reusable blocks of code that perform specific tasks.
• Objects: Collections of key-value pairs representing data and methods.
• Arrays: Ordered lists of values, allowing efficient data storage and manipulation.
• Scope: Determines the visibility of variables within different parts of a program.
• Closures: Functions that "remember" the variables from their enclosing scope even after the outer function has finished executing.
• Prototypal Inheritance: Objects inherit properties and methods from their prototypes, enabling code reusability.

JavaScript Primitive Data Types

• JavaScript primitive data types include:
  • Number: Represents numeric values.
  • String: Represents textual data.
  • Boolean: Represents truth values (true or false).
  • Null: Represents the intentional absence of a value.
  • Undefined: Represents a variable that has not been assigned a value.
• Objects are not primitive data types in JavaScript.

JavaScript and Multithreading

• JavaScript does not have built-in support for multithreading.
• It uses a single thread to execute code, but utilizes asynchronous programming to simulate parallel execution.

Compiled vs. Interpreted Languages: Key Difference

• Compiled languages translate the entire source code into machine code before execution.
• Interpreted languages execute the source code line by line, without a separate compilation step.

Advantages of Functions in JavaScript

• Code Reusability: Functions can be called multiple times, reducing code repetition.
• Modularity: Functions break down complex programs into smaller, manageable units.
• Abstraction: Functions hide implementation details, simplifying code use and maintenance.

JavaScript: Compiled or Not?

• JavaScript is not a compiled language similar to C++.
• While some JavaScript engines use compilation as an optimization step, it's not a fundamental requirement for JavaScript execution.

V8: JavaScript Engine Type

• V8 is a Just-In-Time (JIT) compiler used by Chrome and Node.js.
• It dynamically compiles and optimizes JavaScript code during runtime.

Passing Primitive Types in JavaScript

• When passing primitive types to functions in JavaScript, it's done by value.
• This means a copy of the primitive value is passed, and the function operates on the copy.

Understanding Node.js

• Node.js is a JavaScript runtime environment built on the V8 engine.
• It allows JavaScript to be used for server-side programming, enabling web applications and backend services.

Terms and Descriptions

• Callbacks: Functions passed as arguments to other functions, executed after a specified event or task completes.
• Promise: An object representing the eventual result of an asynchronous operation, handling success or failure scenarios.
• Event Loop: A mechanism that continuously checks for events, triggers callbacks, and executes the next task in the queue.

JavaScript: Synchronous and Asynchronous Programming

• JavaScript supports both synchronous and asynchronous programming paradigms.
• Synchronous code runs in sequential order, waiting for each line to complete before proceeding.
• Asynchronous code allows tasks to run independently, without blocking the execution of other code.

Purpose of Callbacks

• The main purpose of passing functions as callbacks is to enable asynchronous programming.
• Callbacks are executed after the asynchronous operation completes, providing a mechanism to handle results or errors.