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data type

In programming, a data type is a classification that specifies which type of value a variable or expression can hold. JavaScript has several built-in data types, including:

String: a sequence of characters, enclosed in single or double quotes. For example: "hello" or 'world'.

// String
let name = "John";
console.log(name); // Output: "John"

Number: numeric values, including integers and floating-point values. For example: 42 or 3.14.

// Number
let age = 30;
console.log(age); // Output: 30

Boolean: a value that can be either true or false.

// Boolean
let isStudent = false;
console.log(isStudent); // Output: false

Undefined: a value that indicates a variable has been declared but has not been assigned a value.

// Undefined
let address;
console.log(address); // Output: undefined

Symbol: a unique and immutable data type that can be used as an identifier for object properties.

// Symbol
let sym = Symbol("uniqueId");
console.log(sym); // Output: Symbol(uniqueId)

Object: a collection of properties and methods.

// Object
let person = {
 name: "John",
 age: 30
};
console.log(person); // Output: { name: "John", age: 30 }

Array: a special type of object that holds a list of values.

// Array
let colors = ["red", "green", "blue"];
console.log(colors); // Output: ["red", "green", "blue"]

Function: a block of code that can be executed when called.

// Function
function add(a, b) {
 return a + b;
}
console.log(add(2, 3)); // Output: 5

JavaScript also supports a special data type called null, which represents the absence of a value or object.

It's also important to note that JavaScript is a loosely typed language, which means that variables do not have to be declared with a specific data type, and their data type can change at runtime.

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