Learn the key differences between how primitive and reference data types are stored and passed.
JavaScript data types are categorized into two main groups: primitive types and reference types. This distinction is crucial because it dictates how values are stored in memory and how they behave when they are assigned to other variables or passed to functions. The primitive types are: `String`, `Number`, `Boolean`, `null`, `undefined`, `Symbol`, and `BigInt`. Primitives are stored directly in the location that the variable accesses. When you assign a primitive value to another variable, you are making a copy of that value. Therefore, changing the second variable does not affect the original. This is known as 'pass by value'. On the other hand, reference types include `Object`, `Array`, and `Function`. When you create a reference type, the variable doesn't hold the actual object in memory; instead, it holds a reference (or a pointer) to the memory location where the object is stored. When you assign a reference type to another variable, you are only copying the reference, not the object itself. Both variables now point to the same object in memory. This means if you modify the object through one variable, the change will be visible through the other variable as well. This is known as 'pass by reference'. Understanding this difference is vital for debugging and predicting how your data structures will behave, especially when working with complex objects and functions.