Pass by Reference or Pass by Value in JavaScript: How Does It Work?

Pass by Reference vs. Pass by Value in JavaScript

In JavaScript, the question of whether variables are passed by reference or by value has been a subject of confusion. To clarify, primitive data types such as numbers and strings are passed by value, meaning that a copy of the original value is created. Any changes made to this copy do not affect the original variable.

However, objects and arrays, which are complex data types, are passed by "copy of a reference." This means that when an object or array is passed to a function, a reference to that object or array is created, and any modifications made to the reference still affect the original object or array.

The my Parameter in the Rectangle Function

In the example provided, the my parameter in the rectangle function is an illustration of this concept. Inside the function, the my.l and my.w properties are modified, which affects the original object. If the my parameter was removed, the area function within the rectangle function would not have access to these properties.

Closure vs. Direct Modification

It's important to note that this behavior does not correspond to a closure, where a function returns a function with access to the local variables of the parent function. Instead, it is the result of the "copy of a reference" behavior for objects, allowing modifications to the reference to impact the original object.

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