number data type represents integer, float, exponential value, hexadecimal, octal and
23.3, 45.02, 12e2, 10e-1 etc.
String is a data type which is used to store texts, character or sentences. It is created by
enclosing text data in single or double quotes.
boolean is a data type which has two values true and false.
is used for yes-no, on-off purposes.
undefined are the variables which are defined but have not been assigned value to them.
null has only one value, the null.
null is different from
undefined. null is nor equal to "" neither equal to 0.
null means there is
Symbol is another primitive data type. It can be created by calling Symbol().
symbols are unique every time it is invoked.
non-primitive data types are object based or methods. Other data types are called
because they can only hold one type of data but
non-primitive data types can hold different types
of data as a collection. Basically there are three data type in this
object is a non-primitive data type; it holds data in the form of key-value pairs. It stores
collections of different types of data.
The property key is always a string, but the value could have any data type.
Here is a simple example to show how to create objects and use them.
Array is a non-primitive data type which is used to store multiple values in a single variable
which is accessed through index value. Each value stored in the
array has a position value which
starts with 0, known as index of array.
To get array value we write name_of_array[position]. So if name the is
arr, then the first value will be
arr, second value will be
arr and so
Here is an example of an array. We will learn in detail in the coming chapter.
function can be assigned to some variable. See example below. We will learn about function in
get data type of variable "a" you can write
typeof a or
typeof operator is used when you need to get data type of some variable to perform some task.
typeof operator gives some unexpected results shown below so be careful when using it.