What are the two data types categories in Node.js?

In Node.js, data types are primarily categorized into two main types: Primitive Types and Reference Types.

Primitive Types

Primitive types are stored directly in the Stack. These types include:

• Number: Used for representing integers or floating-point numbers, such as 123 or 3.14.
• String: Used for representing text, such as "Hello, World!".
• Boolean: Represents logical truth values, with only two values, true and false.
• Undefined: When a variable is declared but not assigned a value, its value is undefined.
• Null: Represents the absence of any value, typically used to indicate empty or non-existent values.
• Symbol: A type introduced in ES6, used for creating unique identifiers.

Reference Types

Reference types are stored in the Heap, accessed via pointers stored in the Stack. These types include:

• Object: The most basic reference type, capable of storing multiple values of different types within an object. For example:

  javascript
  let person = {
    name: "Alice",
    age: 25
  };

• Array: Used for storing ordered collections of data. For example:

  javascript
  let numbers = [1, 2, 3, 4, 5];

• Function: Functions are also object types, which can be assigned to variables and have properties and methods. For example:

  javascript
  function greet(name) {
    return "Hello, " + name + "!";
  }

Example In real-world development, we frequently handle various data types. For instance, when writing a function to process user input data and store it in a database, you might use strings (for user names and addresses), numbers (for age or phone numbers), and even objects to organize this data, as shown below:

javascript
function storeUserData(name, age, address) {
    let userData = {
        userName: name,
        userAge: age,
        userAddress: address
    };
    database.save(userData);
}

In this example, name, age, and address are passed as arguments to the function using primitive types, while userData is an object used to consolidate these data and store them as a single unit.