In JavaScript, threading is handled in a unique way because of its event-driven, single-threaded nature. However, modern JavaScript has introduced ways to handle parallelism through mechanisms like Web Workers.

Execution Context and hoisting: An Execution Context is an abstract concept in JavaScript that represents the environment in which the code is executed. It contains all the information required to run a piece of code, such as variable bindings, the scope chain, and the value of this. Whenever a function is called, or global code is executed, JavaScript creates a new execution context.

There are memory creation phase and code execution phase.

Hoisting refers to the process by which the JavaScript interpreter moves variable and function declarations to the top of their containing scope (global or function scope) before code execution. This happens during the creation phase of the execution context. note Variables declared with let and const are hoisted as well, but they are placed in a “temporal dead zone” until they are initialized. Accessing them before initialization results in a ReferenceError.

Asynchronous works under the hood, Task Queue and Event loop. JavaScript is a single-threaded, non-blocking language that handles asynchronous operations through a combination of a task queue (also known as the message queue) and the event loop. Together, they enable JavaScript to perform non-blocking, asynchronous operations like fetching data, handling events, and working with timers while still running on a single thread.

In Python, threads of execution are handled with native threads but constrained by the Global Interpreter Lock (GIL) in the CPython implementation. Python can create multiple threads, but only one thread can execute Python bytecode at a time.

Python’s threading module provides an interface to create threads. However, due to the GIL, threads are better suited for I/O-bound tasks where the thread is waiting (e.g., network operations, file I/O).