Pass by Value or Pass by Reference?

JavaScript is often described as a "pass-by-value" language, but this can sometimes be a bit misleading. The behavior of passing values to functions in JavaScript is more accurately described as "pass-by-sharing" or "pass-by-reference for objects, but pass-by-value for primitives." Let's break down what this means:

Primitives (Pass-by-Value)

In JavaScript, primitive data types such as numbers, strings, booleans, null, and undefined are passed by value when they are used as arguments in functions. This means that when you pass a primitive value to a function, a copy of that value is created within the function scope, and any changes made to the parameter within the function do not affect the original value outside the function.

Objects and Arrays (Pass-by-Sharing)

JavaScript objects (including arrays and functions) are more complex data types that are stored by reference in memory. When you pass an object to a function, you're actually passing a reference to the same object in memory, not a copy of the object. However, it's crucial to understand that the reference itself is passed by value. This means that changes made to the properties or elements of the object within the function are reflected outside the function, as you're working with the same object in memory.