What are the various data types in JavaScript?

JavaScript has a variety of data types that are categorized into two groups: primitive and non-primitive (complex) types.

Primitive Data Types

These data types are immutable and stored by value.

1. Number Represents both integer and floating-point numbers.

   let age = 30;
   let price = 19.99;

2. String Represents a sequence of characters.

   let name = 'Alice';

3. Boolean Represents a logical value: true or false.

   let isValid = true;

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

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

5. Null Represents an explicitly empty or non-existent value.

   let y = null;

6. BigInt (ES2020) Represents integers with arbitrary precision.

   let largeNumber = 123456789012345678901234567890n;

7. Symbol (ES2015) Represents a unique and immutable identifier.

   let sym = Symbol('unique');

Non-Primitive (Complex) Data Types

These are mutable and stored by reference.

1. Object Used to store collections of key-value pairs or more complex entities.

   let person = { name: 'Alice', age: 30 };

2. Array (a special type of Object) Represents an ordered list of values.

   let fruits = ['apple', 'banana', 'cherry'];

3. Function (a callable Object) Represents executable code.

   function greet() {
     return 'Hello!';
   }

4. Date (built-in Object) Represents dates and times.

   let now = new Date();

5. Other Built-in Objects Examples include Map, Set, WeakMap, and WeakSet for specialized data structures.

Dynamic Typing

JavaScript is dynamically typed, meaning variables can hold any data type and change type at runtime.

let data = 42; // Number
data = 'Hello'; // Now a String

Conclusion

Understanding JavaScript's data types is essential for writing robust and bug-free code. Knowing their characteristics, such as mutability and storage, helps developers manage memory and avoid common pitfalls.

References

• MDN Web Docs: JavaScript data types and data structures