Data types in JavaScript
Exploring primitive data types
27 August, 2022
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As the name suggests in this piece we are going to discuss different data types in JavaScript.
JavaScript is a loosely typed language i.e. variables can be declared anywhere for example within a loop or conditional statements. It must also be noted that variables are dynamic in nature i.e. the type of data stored in them can also be changed. Please look at the code below
Before we take a deep dive into different data types it is important to mention that in this article we are only going to discuss primitive data types i.e. data types which are building blocks of other data types (ex: Objects).
In JavaScript there are seven types of primitive data types:
1.
Boolean
2.
Null
3.
Undefined
4.
Number
5.
BigInt
6.
String
7.
Symbol
Before proceeding further it is important to know about the
typeof operator. Data type of a variable can be checked by using the typeof operator as shown in the code belowThe above code will give the following output
Boolean
Boolean type variables can only store boolean values i.e.
true and false. See the code below for better understanding.The above code will result in the following output
String
String type variables store textual data for example, a single character or a complete sentence.
The output of the above code will be as follows
Undefined
A variable that has not been assigned a value is of type undefined.
Null
A variable is of type null if it has been intentionally left blank.
There is difference between null and undefined. A variable is of type null if its value has been intentionally left blank where as variable is of type undefined if its value has not yet been defined.
Null datatype cannot be identified using typeof operator. If a variable containing a null value is passed to a typeof operator it will return object as output.
The output of the above code is given below
Symbol
To understand symbols you will need better understanding of the concepts of immutability in Javascript. I will explain this concept in more details in a follow up article for the time being you just need to understand that symbol data types are immutable and unique.
Number
Number type variables can store double precision floating point numbers in the range of -2^1024 to 2^1024. All the floating point number greater then -(2^-1074) and less then 2^{-1074} are converted to 0. All the negative floating point integers less then -2^{1024} are converted to negative infinity and all the numbers greater then 2^1024 are converted to positive infinity.
Also it must be noted that numbers data type can store integers in the range of -2^53 -1 and 2^53 -1.
If you want to check which if a value can be stored as a number data type, the following refrences could be useful:
Number.MAX_SAFE_INTEGERis the the largest integer value that number can storeNumber.MIN_SAFE_INTEGERis the smallest integer that number can store.Number.MAX_VALUEis the largest positive floating point value that number can store.Number.MIN_VALUEis the smallest floating point value that number can store.- Number.MIN_VALUEis the largest negative floating point value that number can store.- Number.MAX_VALUEis the smallest negative floating point value that number can store.
BigInt
BigInt is used to used to store integers which are outside the limit of number data type. Any integer can be converted to a bigInt by using the suffix
n. See code below for better understanding.when the above code is run the output will be the following