Data Types

Javascript is a dynamically typed language and hence though there are data types, variables are not bound to them. In short, a variable can hold any type of data. Same variable can be a number or string or boolean or any other value. Javascript will not throw any error even if you assign a string value to integer variable.

There are 8 different types of data types present in Javascript.

1. Number

Number datatype represents both integers and floating values. Also, it represents Infinity and NaN values as well.

Example

let x = 999;

2. String

String datatype represents text or you can say series of characters. You can use double quotes (" ") or single quotes (' ') or back ticks (``) to represent strings.

Example

// all the three are correct
let x ="OneCompiler";
let y ='OneCompiler';
let z =`OneCompiler`;

3. BigInt

BigInt datatype is used to represent arbitrary length integers as there is a technical limitation for number datatype that it can not represent larger than 9,007,199,254,740,992.

Example

let x = 99999999999999999n;

4. Null

Null is a special value which is used to represent nothing or no value or unknown value.

Example

let x = null;

5. Undefined

Undefined is also a special value which is used to represent value is not assigned. This is predominantly used to check if a variable is assigned or not.

Example

let x;
console.log(x);

6. Boolean

Boolean datatype represents boolean values: true or false.

Example

let x = true;

7. Symbol

Symbol is a primitive data type introduced in ES6 that represents a unique identifier. Each Symbol value is unique and cannot be recreated.

Example

let id = Symbol('id');
let anotherId = Symbol('id');
console.log(id === anotherId); // false

8. Object

All the above seven datatypes are called primitive datatypes as they contain some value. Object datatype represents complex entities which consists of key-value pairs. Objects can be created using curly brackets({ }).

Example

let employee = {  // object
     "name" : "foo", //object property
     "last name" : "bar", //object property
     "id"   : 123 //object property
};

Let's us see in-detail about Objects in further topics.

Summary

Data Type	Description
number	Represents numbers like integers, floating-values etc
string	represents one or more characters
bigint	represents integers of arbitrary length
null	represents unknown values
undefined	represents undefined values
object	represents complex data structures
boolean	represents either true or false
symbol	represents unique identifiers