JS: Data Types | JavaScript | Tutorials by PiTribe

JavaScript Data Types

In computer science, data is the anything that is meaningful to computer. JavaScript Data Types can be categorized as:

Primitive Types
Trivial Types
Composite Types


var i = 0;
var s = "PiTribe";
var b = true;

JavaScript is a Loosely and Dynamically typed programming language.

Primitive Types

Number
String
Boolean
undefined


typeof 1.2345;
typeof true;
typeof "PiTribe";
var u;
typeof u;

"number" "boolean" "string" "undefined"

number

implicit parsing

explicit parsing

JavaScript parsing functions return the parsed value in the respective data type.

parseInt()


var i = parseInt("3.142857142857143");
console.log(x);

In the example above, value parsed to Integer part i.e. 3.

parseFloat()


var pi = parseFloat("3.142857142857143");
console.log(pi);

In the example above, value parsed to double data type and returns 3.142857142857143.

`undefined`

undefined implies that the variable is virgin i.e. no value been yet set to the variable


var x;
console.log(typeof x);

"undefined"

Trivial Types

null

`null`

Composite Types

Object
Array


typeof {a:1,b:2};
typeof [1,2,3];
typeof function(){};
typeof new Date();

"object" "object" "function" "object"

Object

An object stores multiple values in a single variable.


var o = {"continent":"Asia","countries":55,};
console.log(typeof o, o)
console.log(typeof o.continent, o.continent);
console.log(typeof o.countries, o.countries);

object {continent: 'Asia', countries: 55} string Asia number 55

Array

JavaScript array within [ and ], store multiple values of any JavaScript data type, seperated by comma ,.

var arr = ["Earth", 7, 3.14, true, {"name":"Abc Xyz", id:12345}]

In the code above, "Earth" is a string, 7 is an integer number, 3.14 is a float number, true is the boolean value and {"name":"Abc Xyz", id:12345} is a JSON value.

Data Type means what kind of information being stored in a program memory.
JavaScript is a Loosely and Dynamically typed programming language