Datatypes are used to hold the values of variables. JavaScript has two types of datatypes.
·
Primitive
data types
· Non-primitive data types
Java script is a dynamic type. It is not
important to mention the datatype earlier. Use “var” for variable.
Primitive data types:
Javascript has 5 primitive data types.
They are listed below.
Boolean: it represents zero or one
value.
Number: it represents numbers.
String :it represents sequence of
characters.
Null : it represents no value.
Undefined: if you want to define the
value later, use this data type.
Non- primitive data types:
Javascript has 3 different types of
non-primitive data types. They are given below.
Array: It has a list of similar values
Object: it is a instance of a class.
Regexp: It is for Regular Expressions.
Variables:
Variables are so important for any language. It
specifies the value. In javascript, a key word ”var” is used.
Syntax:
var variablename=value;
Eg:
//assigning numbers
var a=10;
//assigning string
var name=”Jey”;
note: variable name should start with
alphabets(lowercase or uppercase), underscore(_),dollar($). These variables are
case sensitive.
Variables can be categorized into two.
They are
Local variables: Variable’s scope is
within the block.
Global variables: Variable’s scope is for
the entire module.
Examples are shown
as below…
Addition
of three numbers in javascript(Eg: local variable)
<!DOCTYPE
html>
<html>
<head>
</head>
<body>
<script
language="javascript">
var a=10; //
local variable
var b=3; //
local variable
var c=5; //
local variable
var d=a+b+c;
document.writeln("The
sum is:"+d);
</script>
</body>
</html>
Output:
Pop up message
display in javascript (Eg: Global variable)
<html>
<body>
<script>
var
value="good vibes";//global variable
function
a1(){
alert(value);
}
a1();
</script>
</body>
</html>
Output:
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