#4 - JavaScript Data Types

JavaScript Data Types
programiz.com/javascript/data-types
There are different types of data that we can use in a JavaScript program. For example,
const x = 5;
const y = "Hello";
Here,
5 is an integer data.
"Hello" is a string data.
There are eight basic data types in JavaScript. They are:
Data Description Example

Types
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 denotes a null value let a = null;
Symbol data type whose instances are unique and let value =
immutable 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:
1/5
Single quotes: 'Hello'
Double quotes: "Hello"
Backticks: `Hello`
For example,
//strings example
const name = 'ram';
const name1 = "hari";
const 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,
const number1 = 3;
const number2 = 3.433;
const number3 = 3e5 // 3 * 10^5
A number type can also be +Infinity, -Infinity, and NaN (not a number). For example,
const number1 = 3/0;

console.log(number1); // Infinity
const number2 = -3/0;

console.log(number2); // -Infinity
// strings can't be divided by numbers

const number3 = "abc"/3;
console.log(number3); // 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,
2/5
// BigInt value
const value1 = 900719925124740998n;
// Adding two big integers

const result1 = value1 + 1n;
console.log(result1); // "900719925124740999n"
const value2 = 900719925124740998n;
// Error! BitInt and number cannot be added

const result2 = value2 + 1;
console.log(result2);
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 logical entities. Boolean represents one of two values: true or
false. It is easier to think of it as a yes/no switch. For example,
const dataChecked = true;

const valueCounted = false;
You will learn more about booleans in the JavaScript Comparison and Logical Operators
tutorial.
JavaScript undefined
The undefined data type represents value that 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); // undefined
It is also possible to explicitly assign a variable value undefined. For example,
let name = undefined;

console.log(name); // 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.
3/5
JavaScript null
In JavaScript, null is a special value that represents empty or unknown value. For
example,
const 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
const value1 = Symbol('hello');

const 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,
const student = {
firstName: 'ram',
lastName: null,
class: 10
};
You will learn about JavaScript Objects in later tutorials.
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,
4/5
// 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,
const name = 'ram';

typeof(name); // returns "string"
const number = 4;
typeof(number); //returns "number"
const valueChecked = true;

typeof(valueChecked); //returns "boolean"
const 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.
5/5

#4 - JavaScript Data Types

Uploaded by

Copyright:

Available Formats

#4 - JavaScript Data Types

Uploaded by

Document Information

Original Description:

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

#4 - JavaScript Data Types

Uploaded by

Copyright:

Available Formats

JavaScript Data Types

There are eight basic data types in JavaScript. They are:

Data Description Example

String represents textual data 'hello', "hello world!"

Number an integer or a floating-point number 3, 3.234, 3e-2 etc.

BigInt an integer with arbitrary precision 900719925124740999n , 1n

Boolean Any of two values: true or false true and false

undefined a data type whose variable is not initialized let a;

null denotes a null value let a = null;

Object key-value pairs of collection of data let student = { };

const number1 = 3/0;

const number2 = -3/0;

// strings can't be divided by numbers

A BigInt number is created by appending n to the end of an integer. For example,

// Adding two big integers

const value2 = 900719925124740998n;

// Error! BitInt and number cannot be added

const dataChecked = true;

It is also possible to explicitly assign a variable value undefined. For example,

let name = undefined;

Note: It is recommended not to explicitly assign undefined to a variable. Usually, null is

const number = null;

The code above suggests that the number variable is empty.

Note: null is not the same as NULL or Null.

// two symbols with the same description

const value1 = Symbol('hello');

Visit JavaScript Symbol to learn more.

You will learn about JavaScript Objects in later tutorials.

// data is of integer type

// data is of string type

const name = 'ram';

const valueChecked = true;

You might also like