Primitive (values) vs Objects (references)

A variable can hold one of two value types: primitive values or reference values.

  • Primitive values are data that are stored on the stack.
  • Primitive value is stored directly in the location that the variable accesses.
  • Reference values are objects that are stored in the heap. (aka it’s stored elsewhere to preserve memory space and the variable is just a link to it).
  • Reference value stored in the variable location is a pointer to a location in memory where the object is stored.
  • 5 Primitive types: Undefined, Null, Boolean, Number, or String.  Anything else is an object.

The Basics:

Objects are aggregations of properties. A property can reference an object or a primitive.

Primitives are values, they have no properties.

Some Examples:


Primitive (values) vs Objects (references)

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