JAVASCRIPT PART 2: UNDERSTANDING BASIC DATA TYPES AND VARIABLES IN JAVASCRIPT
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Data Types and Variables in JavaScript
JavaScript is a dynamic programming language, which means that it can use different data types without declaring them explicitly. In this article, we’ll discuss the basic data types and variables in JavaScript.
Data Types in JavaScript
JavaScript has seven basic data types, which are:
- Number
- String
- Boolean
- Null
- Undefined
- Object
- Symbol (added in ECMAScript 6)
Number
The Number data type represents numeric values. It includes integers, decimals, and special numeric values such as Infinity and NaN. You can declare a Number variable as follows:
var a = 10;
var b = 3.14;
var c = Infinity;
var d = NaN;
String
The String data type represents a sequence of characters. You can declare a String variable as follows:
var a = "Hello";
var b = 'World';
Boolean
The Boolean data type represents a logical value that can be either true or false. You can declare a Boolean variable as follows:
var a = true;
var b = false;
Null
The Null data type represents a deliberate non-value. You can declare a Null variable as follows:
var a = null;
Undefined
The Undefined data type represents a variable that has not been assigned a value. You can declare an Undefined variable as follows:
var a;
Object
The Object data type represents a collection of properties. You can declare an Object variable as follows:
var person = {
name: "John",
age: 30,
city: "New York"
};
Symbol
The Symbol data type represents a unique identifier. You can declare a Symbol variable as follows:
var sym1 = Symbol();
var sym2 = Symbol("foo");
Variables in JavaScript
In JavaScript, you can declare a variable using the var, let, or const keyword.
var
The var keyword is used to declare a variable that can be reassigned. For example:
var a = 10;
a = 20;
let
The let keyword is used to declare a variable that can be reassigned within its block scope. For example:
let a = 10;
if (true) {
let a = 20;
}
const
The const keyword is used to declare a variable that cannot be reassigned. For example:
const PI = 3.14;
Example Program
Here’s an example program that demonstrates the use of variables and data types in JavaScript:
// Number data type
let a = 42;
console.log("Value of a:", a);
console.log("Data type of a:", typeof a);
// String data type
let b = "Hello, World!";
console.log("Value of b:", b);
console.log("Data type of b:", typeof b);
// Boolean data type
let c = true;
console.log("Value of c:", c);
console.log("Data type of c:", typeof c);
// Null data type
let d = null;
console.log("Value of d:", d);
console.log("Data type of d:", typeof d);
// Undefined data type
let e;
console.log("Value of e:", e);
console.log("Data type of e:", typeof e);
// Object data type
let f = {name: "John", age: 30};
console.log("Value of f:", f);
console.log("Data type of f:", typeof f);
// Array data type
let g = [1, 2, 3, 4, 5];
console.log("Value of g:", g);
console.log("Data type of g:", typeof g);
Output:
Value of a: 42 Data type of a: number Value of b: Hello, World! Data type of b: string Value of c: true Data type of c: boolean Value of d: null Data type of d: object Value of e: undefined Data type of e: undefined Value of f: { name: 'John', age: 30 } Data type of f: object Value of g: [ 1, 2, 3, 4, 5 ] Data type of g: object
Conclusion
In this article, we discussed the basic data types in JavaScript and how to declare and use variables. By understanding these fundamental concepts, you’ll be able to write more complex programs in JavaScript.
JavaScript Beginner Tutorial Series
- JavaScript Part 1: Setup and Introduction
- JAVASCRIPT PART 2: Understanding Basic Data Types And Variables In JavaScript
- JavaScript PART 3: OPERATORS AND EXPRESSIONS IN JavaScript
- JavaScript PART 4: CONTROL FLOW STATEMENTS IN JavaScript
- JavaScript PART 5: FUNCTIONS IN JavaScript
- JavaScript Part 6: Arrays In JavaScript
- JavaScript Part 7: String Manipulation In JavaScript
- JavaScript Part 8: Object-Oriented Programming In JavaScript (Classes and Objects)
- JavaScript Part 9: Object-oriented Programming In JavaScript (OOP Pillars)
- JavaScript Part 10: Exception Handling in JavaScript