In this article, we will learn about Datatypes in JavaScript.
In a JavaScript program, we can use different data types. For example,
const x = 5; const y = “JavaScript”; |
In this example
- ‘5’ is integer data.
- ‘Hello’ is string data.
Contents
JavaScript DataTypes
In JavaScript, there are eight basic data types. They are as follows:
DataTypes | Description | Example |
---|---|---|
String | represents textual data | ‘hello’, “hello world” etc |
Number | an integer or a floating-point number | 5, 5.134, 3e -2 etc. |
BigInt | an integer with arbitrary precision | 900719925124740999n, 2n etc. |
Boolean | Any of two values: true or false | true and false |
undefined | a data type whose variable is not initialized | let x; |
null | denotes a null value | let ax = null; |
Symbol | datatype whose instances are unique and immutable | let message = Symbol(‘hello’); |
Object | key-value pairs of collection of data | let passengers = { }; |
Except for Object, all data types are primitive, whereas Object is non-primitive.
Note: The Object data type (non-primitive type) can store collections of data, whereas the primitive data type can only store a single data.
JavaScript String
The text is stored in a string. Quotes are used to surround strings in JavaScript:
- Single quotes: ‘JavaScript’
- Double quotes: “JavaScript”
- Backticks: `JavaScript`
For example:
//strings example const name = ‘Ramesh’; const name1 = “Suresh”; const result = `The names are ${name} and ${name1}`; |
Single and double quotes are nearly identical and can be used interchangeably.
When you need to include variables or expressions in a string, you usually use backticks. As shown above, this is accomplished by wrapping variables or expressions in $variable or expression.
JavaScript Number
Integer and floating numbers are represented by the number (decimals and exponentials). For example:
const number1 = 5; const number2 = 5.143; const number3 = 5e3 // 5 * 10^3 |
A number type can also be +Infinity, -Infinity, and NaN (not a number). For example:
const number1 = 5/0; console.log(number1); // Infinity const number2 = -5/0; console.log(number2); // -Infinity // strings can’t be divided by numbers const number3 = “xyz”/5; console.log(number3); // NaN |
JavaScript BigInt
The Number type in JavaScript can only represent numbers that are less than (253 – 1) and greater than – (253 – 1). However, if you need to use a larger number, the BigInt data type can be used.
By appending n to the end of an integer, a BigInt number is created. For example:
// BigInt value const value1 = 900711231242353252314n; // Adding two big integers const result1 = value1 + 1n; console.log(result1); // “n” const value2 = 486685465416549898498n; // Error! BigInt and number cannot be added const result2 = value2 + 1; console.log(result2); |
Output:
900711231242353252315n Uncaught TypeError: Cannot mix BigInt and other types |
Note: BigInt was introduced in a newer version of JavaScript, and many browsers, including Safari, do not support it.
JavaScript Boolean
Logical entities are represented by this data type. True or false is the value of a Boolean expression. It’s more straightforward to think of it as a yes/no switch. For example:
const dataAnalysed = true; const valueCounted = false; |
JavaScript undefined
The undefined data type represents an unassigned value. If a variable is declared but not assigned a value, the variable’s value will be undefined. For example:
let number; console.log(number); // undefined |
It’s also possible to make a variable’s value undefined explicitly. For instance:
let number = undefined; console.log(number); // undefined |
Note: It is not recommended to assign undefined to a variable explicitly. Null is typically used to assign a variable an ‘unknown’ or ’empty’ value.
JavaScript null
Null is a special value in JavaScript that represents an empty or unknown value. For example:
const number = null; |
The code above suggests that the name variable is empty.
Note: that null is not similar to NULL or Null.
JavaScript Symbol
This data type was added to JavaScript in a later version (from ES2015).
The data type of a value A symbol value is another term for a symbol. A symbol is an immutable, one-of-a-kind primitive value. As an example,
// two symbols with the same description const message1 = Symbol(‘hello’); const message2 = Symbol(‘hello’); |
Despite the fact that both value1 and value2 contain the word “hello,” they are distinct because they are of the Symbol type.
JavaScript Object
A complex data type that allows us to store collections of data is called an object. For example:
const passenger = { firstName: ‘suresh’, lastName: null, coach: D2 }; |
JavaScript Type
JavaScript is a loosely typed (dynamically typed) language. The data type of variables is automatically determined by JavaScript.
It also means that a variable can start out as one data type and later change to another. As an example,
// value is of undefined type let value; // value is of integer type value = 5; // value is of string type value = “JavaScript”; |
JavaScript typeof
The typeof operator can be used to determine the type of a variable. As an example,
const name = ‘shyam’; typeof(name); // returns “string” const number = 7; typeof(number); //returns “number” const valueChecked = false; typeof(valueChecked); //returns “boolean” const a = null; typeof(a); // returns “object” |
It’s worth noting that for the null type, typeof returned “object.” Since the first release of JavaScript, this has been a known issue.
That’s all about the Datatypes in JavaScript.
You may like Variables and Constants in JavaScript.
Hope this article will guide you to recognize about the Datatypes in JavaScript that you needed and still if you have any problems or queries regarding this, post them in the comments section and we will be glad to assist you.
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