JavaScript Data Types
- JavaScript data types define what kind of values a variable can hold and how those values behave in a program.
- They determine how data is stored in memory and how operations like comparison, calculation, and conversion work.
Primitive Data Type
- Primitive data types in JavaScript represent simple, immutable values stored directly in memory, ensuring efficiency in both memory usage and performance.
1.Number
- The Number data type in JavaScript includes both integers and floating-point numbers. Special values like
Infinity,-Infinity, andNaNrepresent infinite values and computational errors, respectively.
let n1 = 2;
console.log(n1) // 2
let n2 = 1.3;
console.log(n2) // 1.3
let n3 = -Infinity;
console.log(n3) // -Infinity
let n4 = 'something here too' / 2;
console.log(n4) // NaN
2.String
- A String in JavaScript is a series of characters that are surrounded by quotes. There are three types of quotes in JavaScript, which are.
let s1 = "Hello There";
console.log(s1); // Hello There
let s2 = 'Single quotes work fine';
console.log(s2); // Single quotes work fine
let s3 = `can embed ${s1}`;
console.log(s3); // can embed Hello There
3.Boolean
- The boolean type has only two values i.e.
trueandfalse.
let b1 = true;
console.log(b1); // true
let b2 = false;
console.log(b2); // false
4.Null
- The special
nullvalue does not belong to any of the default data types. It forms a separate type of its own which contains only the null value.
let age = null;
console.log(age) // error
// TypeError: can't access property "stack", exception is null
The 'null' data type defines a special value that represents nothing, or empty value.
5.Undefined
- A variable that has been declared but not initialized with a value is automatically assigned the undefined value. It means the variable exists, but it has no value assigned to it.
let a;
console.log(a);
// TypeError: can't access property "stack", exception is undefined
6.Symbol (Introduced in ES6)
- Symbols, introduced in ES6, are unique and immutable primitive values used as identifiers for object properties. They help create unique keys in objects, preventing conflicts with other properties.
let s1 = Symbol("Geeks");
let s2 = Symbol("Geeks");
let s3 = s1;
console.log(s1 == s2); // false
console.log(s1 == s3); // true
7. BigInt (Introduced in ES2020)
-
BigIntis a built-in object that provides a way to represent whole numbers greater than 253. The largest number that JavaScript can reliably represent with the Number primitive is 253, which is represented by the MAX_SAFE_INTEGER constant.
let b = BigInt("123456789345678");
console.log(b); // 123456789345678
Non-Primitive Data Types
- The data types that are derived from primitive data types are known as non-primitive data types. It is also known as derived data types or reference data types.
1.Object
- JavaScript objects are key-value pairs used to store data, created with {} or the new keyword. They are fundamental as nearly everything in JavaScript is an object.
let myObj = {
type: "Zoho",
location: "Chennai"
}
console.log(myObj.type) // Zoho
2.Arrays
- An Array is a special kind of object used to store an ordered collection of values, which can be of any data type.
let a1 = [1, 2, 3, 4, 5];
console.log(a1);
let a2 = [1, "two", { name: "Object" }, [3, 4, 5]];
console.log(a2);
3.Function
- A function in JavaScript is a block of reusable code designed to perform a specific task when called.
// Defining a function to greet a user
function greet(name)
{
return "Hello, " + name + "!";
}
// Calling the function
console.log(greet("Ajay"));
4.Date Object
- The Date object in JavaScript is used to work with dates and times, allowing for date creation, manipulation, and formatting.
// Creating a current date and time
let currentDate = new Date();
// Displaying the current date and time
console.log(currentDate); // "2026-06-02T13:25:27.401Z"
https://www.geeksforgeeks.org/javascript/javascript-data-types/
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Data_structures
Top comments (1)
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