(JavaScript Tutorials for Beginners)
In this end-to-end example, you will learn – JavaScript tutorials for Beginners – JavaScript Data Types.
JavaScript Data Types
In this tutorial, you will learn about the various data types available in JavaScript with the help of examples.
As suggested by the name data types, it refers to types of data that you can use in your program. For example,
let x = 5;
let y = "Hello";
Here,
- 5 is an integer data.
- “Hello” is a string data.
JavaScript Data Types
There are eight basic data types in JavaScript. They are:
Data Types | Description | Example |
String |
represents textual data | 'hello' , "hello world!" etc |
Number |
an integer or a floating-point number | 3 , 3.234 , 3e-2 etc. |
BigInt |
an integer with arbitrary precision | 900719925124740999n , 1n etc. |
Boolean |
Any of two values: true or false | true and false |
undefined |
a data type whose variable is not initialized | let a; |
null |
special keyword denoting a null value |
let a = null; |
Symbol |
data type whose instances are unique and immutable | let value = Symbol('hello'); |
Object |
key-value pairs of collection of data | let student = { }; |
Here, all data types except Object
are primitive data types, whereas Object
is non-primitive.
Note: The Object
data type (non-primitive type) can store collections of data, whereas primitive data type can only store a single data.
JavaScript String
String
is used to store text. In JavaScript, strings are surrounded by quotes:
- Single quotes:
'Hello'
- Double quotes:
"Hello"
- Backticks:
`Hello`
For example,
//strings example
let name = 'ram';
let name1 = "hari";
let result = `The names are ${name} and ${name1}`;
Single quotes and double quotes are practically the same and you can use either of them.
Backticks are generally used when you need to include variables or expressions into a string. This is done by wrapping variables or expressions with ${variable or expression}
as shown above.
You will learn about the use of backticks in the JavaScript String tutorial.
JavaScript Number
Number
represents integer and floating numbers (decimals and exponentials). For example,
let number1 = 3;
let number2 = 3.433;
let number3 = 3e5 // 3 * 10^5
A number type can also be +Infinity
, -Infinity
, and NaN
(not a number). For example,
let number1 = 3/0;
console.log(count); // returns Infinity
let number2 = -3/0;
console.log(count1); // returns -Infinity
// strings can't be divided by numbers
let number3 = "abc"/3;
console.log(number3); // returns NaN
JavaScript BigInt
In JavaScript, Number
type can only represent numbers less than (253 – 1) and more than -(253 – 1). However, if you need to use a larger number than that, you can use the BigInt
data type.
A BigInt
number is created by appending n to the end of an integer. For example,
// BigInt value
let value = 900719925124740998n;
// Adding two big integers
let value1 = value + 1n;
console.log(value1); // returns "900719925124740999n"
let value = 900719925124740998n;
// Error! BitInt and number cannot be added
let value1 = value + 1;
console.log(value1);
Output
900719925124740999n Uncaught TypeError: Cannot mix BigInt and other types
Note: BigInt
was introduced in the newer version of JavaScript and is not supported by many browsers including Safari. Visit JavaScript BigInt support to learn more.
JavaScript Boolean
This data type represents the logical entity. Boolean
represents one of two values: true
or false
. It is easier to think of it as a yes/no switch. For example,
let dataChecked = true;
let valueCounted = false;
You will learn more about booleans in the JavaScript Comparison and Logical Operators tutorial.
JavaScript undefined
The undefined
data type represents value is not assigned. If a variable is declared but the value is not assigned, then the value of that variable will be undefined
. For example,
let name;
console.log(name); // returns undefined
It is also possible to explicitly assign a variable value undefined
. For example,
let name = undefined;
console.log(name); // returns undefined
Note: It is recommended not to explicitly assign undefined
to a variable. Usually, null
is used to assign ‘unknown’ or ’empty’ value to a variable.
JavaScript null
In JavaScript, null
is a special value that represents empty or unknown value. For example,
let number = null;
The code above suggests that the number variable is empty.
Note: null
is not the same as NULL or Null.
JavaScript Symbol
This data type was introduced in a newer version of JavaScript (from ES2015).
A value having the data type Symbol
can be referred to as a symbol value. Symbol
is an immutable primitive value that is unique. For example,
// two symbols with the same description
let value1 = Symbol('hello');
let value2 = Symbol('hello');
Though value1 and value2 both contain 'hello'
, they are different as they are of the Symbol
type.
Visit JavaScript Symbol to learn more.
JavaScript Object
An object
is a complex data type that allows us to store collections of data. For example,
let student = {
firstName: 'ram',
lastName: null,
class: 10
};
You will learn about JavaScript Objects in the later tutorial.
JavaScript Type
JavaScript is a dynamically typed (loosely typed) language. JavaScript automatically determines the variables’ data type for you.
It also means that a variable can be of one data type and later it can be changed to another data type. For example,
// data is of undefined type
let data;
// data is of integer type
data = 5;
// data is of string type
data = "JavaScript Programming";
JavaScript typeof
To find the type of a variable, you can use the typeof
operator. For example,
let name = 'ram';
typeof(name); // returns "string"
let number = 4;
typeof(number); //returns "number"
let valueChecked = true;
typeof(valueChecked); //returns "boolean"
let a = null;
typeof(a); // returns "object"
Notice that typeof
returned "object"
for the null
type. This is a known issue in JavaScript since its first release.
Disclaimer: The information and code presented within this recipe/tutorial is only for educational and coaching purposes for beginners and developers. Anyone can practice and apply the recipe/tutorial presented here, but the reader is taking full responsibility for his/her actions. The author (content curator) of this recipe (code / program) has made every effort to ensure the accuracy of the information was correct at time of publication. The author (content curator) does not assume and hereby disclaims any liability to any party for any loss, damage, or disruption caused by errors or omissions, whether such errors or omissions result from accident, negligence, or any other cause. The information presented here could also be found in public knowledge domains.
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