javaScript Variables: types of variables

Vedanth bora

2 min readFeb 8, 2021

As we know, we can assign all sorts of different types to a variable. But javaScript has types.

In particular, it provides primitive types and object types.

— Primitive Types

number
string
boolean
symbol

— and two special types

null
undefined

Lets understand them in detail.

Numbers.

A numeric literal is a number represented in the source code, amd depending on how it’s written, it can be an integer literal or a floating point literal.

integers:

30
5354576
0xCB //hex

floats:

3.14
.124
5.2e4 //5.2 * 10^4

Strings.

A string type is a sequence of characters.
It’s defined in the source code as a string literal, which is enclosed in quotes or double quotes

'A string'
"Another string"//Strings can span across multiple lines by using the backslash"A \
string" //Strings can be joined using the + operator:"A " + "string" // string concatenation//A string can contain escape sequences that can be interpreted when the string is printed, like \n to create a new line.'I\'m a developer'

Booleans.

JavaScript defines two reserved words for booleans which are: true and false.
Many comparision operations == === < >(and so on) return either one or the other.

0
-0
NaN
undefined
null
'' //empty string

null.

null is a special value that indicates the absence of a value.
It’s a common concept in other languages as well, can be known as nil or None in Python for example.

undefined.

undefined indicates that a variable has not been initialized and the value is absent.
It is commonly returned by functions with no returnvalue.
When a function accepts a parameter but that is not set by the caller, it is undefined

//To detect if a value is undefined, you use the construct:typeof variable === 'undefined'

Object Types

Anything that is not primitive type is an object type.
Object types have properties and also have methods that can act on those properties.

typeof 10=== 'number'
typeof '10' === 'string'
typeof {name: 'superman'} === 'object'
typeof [1, 2, 3, 4] === 'object'
typeof false === 'boolean'
typeof undefined === 'undefined'
typeof (() => {}) === 'function'// Any variable has a type assigned. Use the typeofoperator to get a string representation of a type:

hope this helped you understand the different types of Variables in javaScript. If you have any questions please drop me a text. 😄