JavaScript, Global Execution Context Explanation

Global Execution Context Explanation
Explain Global Execution Context in JS.
Answer: In JavaScript, the Global Execution Context is the environment in which top-level JavaScript code is executed. It consists of two main components:
1. Global Object: Also known as the 'window' object in web browsers or 'global' object in Node.js, it serves as the outermost wrapper for JavaScript code. It provides access to built-in functions and objects like 'console', 'Math', 'setTimeout', etc.
2. Global Scope: This is where variables, functions, and objects declared outside of any function reside. Variables declared with 'var', 'let', 'const' outside of functions become properties of the global object. Functions declared at the top level also become methods of the global object.- Creation Phase: During the creation phase of the execution context, JavaScript allocates memory for variables and functions declared with 'var' (for 'let' and 'const', memory is allocated but not initialized with 'undefined'). This is known as variable hoisting.
- Execution Phase: In this phase, JavaScript code is executed line by line. Assignments to variables are made, functions are called, and code runs until completion or an error occurs.
- Scope Chain: Each function in JavaScript creates its own execution context. When a function is executed, it forms a scope chain with the outer scopes, allowing access to variables and functions defined in its outer scope (lexical scoping).
- Context Stack: JavaScript uses a stack-like structure known as the "call stack" to manage execution contexts. When a function is called, a new execution context is created and pushed onto the stack. When the function finishes executing, its context is popped off the stack, returning control to the previous context.
Understanding the Global Execution Context is crucial for grasping how JavaScript manages variables, functions, and their scopes throughout your code.