This content originally appeared on DEV Community and was authored by vicky-ops
javaScript Oh boi!! the defacto language for Web. And for today we will be focusing on it's types mainly its Primitive type .
But before jumping on Primitive type, lets discuss bit about the language itself. Javascript is a dynamic language it basically means variables in javascript are not directly associated with any particular type.
Depending on its type js broadly can be divided upon ::
- Primitive types.
- Objects.
Primitive Type
Primitive Type is immutable by nature, So what does it means,
a piece of code can summarize it nicely.
let number1 = 1;// we are declaring a variable and assigning with a Number 1
number1 = 2;//Here we are reassigning number1 to 2, in any way we are not updating it.
So, As in the comments in the above code we are not mutating the variable simply we are reassigning it. As for every other Primitive type they are immutable in javascript.
In JS we have 7 primitive types ::
1.Number.
2.Big Int.
3.String.
4.Undefined.
5.null(techically object)
6.Boolean
7.Symbol(recent addition the langauge ES2015)
But, we are going too fast right, some people might ask how do get to know its type . Simply we can use typeof operator to check for it, it will be useful so we will try to remember it.
Numeric Type ::
Javascript has two Numeric types
1.Number type
2.BigInt
Number type in javascript are not integers they are floating-
point numbers, Technically double-precision 64-bit binary
format. So below is Code Summary
const num = 1;//variable assignment to a Number type
typeof(num); //will return type of number
console.log(Number.MAX_SAFE_INTEGER);//will return `9007199254740991` as the max safe integer.
console.log(Number.MIN_SAFE_INTEGER);//will return `-9007199254740991` as the min safe integer.
BIG INT comes handy if you want to work on really big numbers even beyond Number.MAX_SAFE_INTEGER or its inverse Number.MIN_SAFE_INTEGER . Mozilla docs wraps it nicely have a look if you want to dive deeply. we will skip to next type😎.
String Type ::
String is fundamental type regardless of whatever type of language it is. Rule of Immutability play's here as well it means when we are adding a character or concatenating two strings we are reassigning the previous string to a new string, not necessarily modifying the old string.
Its fairly a basic data type for any language. So, look at the code below ::
const name = "Richard"//A simple variable declarations with a string assignment
typeof(name)/will return string
Undefined
Yes undefined is a type and it is used implicitely in javascript even if your not using it explicitly. what does it means below code block it clear it out.
let name //say you forgot to assign value to the value, javascript implicitely assigns undefined as its value.
typeof(name);//so it will return undefined as its value.
//avoid undefined in case of intentional empty variable assignment use null instead.
null type
null is a primitive type in javascript, it is represented by literal null. and mostly null represents intentional absence of any value by developer.
But typeof null returns objects type there are many article are out there for this weird behaviour, its a bug to-be precise according to lot of articles.
let name = null;//intentional absence of any value assignment.
typeof(name); //will return object , weird isn't it.
//both undefined & null seems to be same but they are not
console.log(undefined == null);// will return true they are both absent of any value.
console.log(undefined === null);// will return false here cause we are checking both value and type. Their type is different
above code also makes it clear that undefined and null are not same they have some similarity but of different use. be smart before using each of one them.
Boolean type
Boolean types are represented by two literal true and false, yes as simple as that. And Booleans are everwhere from any conditional like if-else,switch to operator like == & ===. So proper understading is mandatory. Code below will clear it out.
const bool = true // will assign true boolean as value to bool variable.
typeof(boo);//will return boolean
if(bool){return "boole= "+bool}// here if block is going to run only if the value bool evalutes to true try changing to false it will not run
Symbol
Symbol is a primitive type in javascript like other types mentioned above. Its Added in ECMAScript 2015 fairly recent addition. unlike others Number,String,null,undefined,boolean it doesn't have any literal it represent it
To create a new Symbol we use global method method like below ::
let userName = Symbol('name')
As with Symbol with each invokation of Symbol()it returns unique private value so Symbol() == Symbol() will be false.
Symbol() == Symbol();//returns false
So, here we are at the end of this post. I made an effort to simplyfy things in javascript which seems daunting from a new developers perspective. javascript have lot of concepts which are needed to-be well understood to leverage the language itself, I am following this amazing github repository for holistic javascript undersanding, Check it guys/gals.
This content originally appeared on DEV Community and was authored by vicky-ops
vicky-ops | Sciencx (2022-04-02T17:15:41+00:00) Primitive type. Retrieved from https://www.scien.cx/2022/04/02/primitive-type/
Please log in to upload a file.
There are no updates yet.
Click the Upload button above to add an update.