Understanding JavaScript Data Types

Primitive Data Types

JavaScript has six primitive data types:

1. String

A sequence of characters used to represent text. Strings can be created using single, double, or backticks quotes.

let name = 'John';
let greeting = "Hello, World!";
let template = `My name is ${name}`;

2. Number

Represents both integer and floating-point numbers. JavaScript does not differentiate between the two.

let age = 30;
let price = 19.99;

3. Boolean

Represents a logical entity and can have only two values: true or false.

let isAvailable = true;
let isCompleted = false;

4. Null

Represents the intentional absence of any object value. It is one of JavaScript's primitive values.

let result = null;

5. Undefined

A variable that has been declared but has not yet been assigned a value.

let x;
console.log(x); 
// undefined

6. Symbol

A unique and immutable primitive value and may be used as the key of an object property.

let sym = Symbol('description');

Non-Primitive Data Type

1. Object

Objects are collections of key-value pairs. Keys are strings (or Symbols) and values can be of any type.

let person = {
  name: 'John',
  age: 30,
  isEmployed: true
};

2. Array

Arrays are a special type of object used for storing ordered collections of values.

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

Type Checking

Use the typeof operator to check the type of a variable.

// string
console.log(typeof 'Hello'); 
// number
console.log(typeof 42); 
// boolean
console.log(typeof true); 
// undefined
console.log(typeof undefined); 
// object
console.log(typeof { name: 'John' }); 
// object
console.log(typeof [1, 2, 3]); 

Conclusion

Understanding JavaScript data types is fundamental for writing robust and error-free code. Remember that JavaScript is dynamically typed, so the type of a variable can change during the execution of the program. Always use the appropriate data type for your variables and leverage the typeof operator for type checking.

Happy coding!

Explanation:

• Primitive Data Types: Detailed explanations and examples for string, number, boolean, null, undefined, and symbol.
• Non-Primitive Data Type: Examples of objects and arrays.
• Type Checking: Demonstrates how to use the typeof operator to check the type of variables.
• Code Blocks: Simplified using standard Markdown code blocks for easier use and readability.