JavaScript Execution Context – How JS Works Behind The Scenes

In JavaScript, understanding the concept of execution context is crucial to comprehend how code is executed behind the scenes. An execution context can be thought of as an environment in which JavaScript code is evaluated and executed. There are three types of execution contexts in JavaScript: the global execution context, function execution context, and eval execution context. The global execution context is the default context where code that is not inside any function is executed.

When a function is invoked, a new function execution context is created, which includes the function’s arguments, local variables, and the reference to the outer environment where the function was declared. This process is known as the creation phase of the execution context. During the execution phase, the code inside the function is run line by line. Understanding how JavaScript manages execution contexts is essential for writing efficient and bug-free code.