In any programming language, there are variables and variables store values. These values can be of different types.
In
Javascript there are 8 different types of data types. Data types define the
type of data that can be stored in the variable and used in the program. These
8 different data types are classified into two types primitive and
non-primitive data types.
Primitive data types: These are basic data types that represent a single value. The following are the primitive data types in JavaScript:
· Number
· String
· BigInt
· Boolean
· Undefined
· Null
· Symbol (added in ECMAScript 6)
Non-primitive data types: These are complex data types that represent a collection of values. The following is the non-primitive data type in JavaScript:
· Object: including arrays, functions, and more.
The
following are different data types in Javascript:
1. Number
A Number
data type implies both positive or negative numbers as well as floating point
numbers. It is also used to represent numbers in exponential form like 2.3e-7
(equivalent to 2.3x10-7).
Some special numerical values like Infinity, -Infinity, NaN are also included in the Number data type.
We get
Infinity value which is a number greater than zero when we divide any number
with zero.
alert(12/0);
// infinity
alert(-12/0);
// infinity
alert(12/-0);
// infinity
NaN ( Not a
Number) is a special value that is obtained due to a undefined mathematical
operation.
alert
(“NaN”/6) //NaN
2. String
String data
type represents textual data or string of characters that are enclosed within
single or double quotes. For example “Apple”, ‘Orange’ etc. Single or double
quotes are not different and indicate same thing.
3. Boolean
Boolean
data type can only contain two values i.e. either True or False.
True means
‘Yes’ and False means ‘No’.
You can also get Boolean values as a result of some comparison.
4. Null
Null data
type in javascript literally represents “nothing”. However, if you use typeof operator for null, it
returns an object type. This is considered a bug in javascipt.
5. Undefined
The
Undefined data type is also stand alone data type like Null and it actually
means “value is not assigned”. When you just declare a variable but do not assign
any value to it, then it has undefined value.
6. BigInt
The Number
data type in Javascript cannot properly store integer values greater than (253
+ 1) and less than -(253 - 1). If we try to store value greater than
these values then a error gets displayed. To accommodate integers of arbitrary length,
we use BigInt type.
Syntax
BigInt (
number)
OR
By appending
‘n’ at the end of the number.
Const
biggInt = 023049823904120980948302984320948n;
7. Symbol
The Symbol
data type which was newly introduced in ES6 is used to create a unique
identifier key that cannot be changed.
We use
Symbol() to create a new primitive symbol data type.
Two Symbols with same description are Unique
Two symbols with same description are not same even they look same.
For example:
let x1 = Symbol(“hi”);
let x2 = Symbol (“hi”);
console.log(x1 === x2); //false
Add Symbol as an Object Key
You can also add Symbol as an Object Key as shown below
You can add symbols as a key in an object using square brackets []. For example,
let rollno = Symbol("rollno");
let person = {
name: "Nikhil",
// adding symbol as a key
[rollno]: 444 // not "rollno": 444
};
console.log(person); // {name: "Nikhil", Symbol(rollno): 123}
The best thing about Symbol is that they are unique and immutable. You can use the same unique Symbol key in another code without duplication issues.
8. Object
The Object
data type is a non-primitive data type in Javascript that is used to store
large collection of data of different data types in key-value pairs. These key
value pairs of objects are called as properties of objects. The values of the
keys can be another objects thus making it possible to create complex nested structure.
The syntax
to declare object is:
const object_name = {
key1: value1,
key2: value2
}
const student = {
name: ‘Nikhil’,
maths: 55,
science: 20,
};
// accessing property
console.log(student.name); // Nikhil
console.log(student[“maths”]); // 55
You can easily access the value of the key in properties using a (.) dot notation or square bracket [] notation.
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