Netscape communications corporation, in 1995 introduced Netscape Navigator 2.0 and LiveScript which was later, called JavaScript. JavaScript runs on browser thus making it platform independent. it has advantage over those languages, which are compiled into machine code before execution. Hence it is also called interpreted language.
JavaScript is an object-based, client side scripting
language. It is a incorporation of HTML and programming language.
JavaScript can also be
used for server side scripting. Client side scripting means which run on client
machine and server side scripting means that runs on a web server. JavaScript
is not very much powerful for server application.
Comparison between JavaScript and Java
JavaScript Java
JavaScript is a script language. Java is a
programming language.
It is an interpreted language. It is a compiler as well as
interpreted Language.
It is not required to declare data type of It
is compulsory to declare data types of variables
the variables of the JavaScript in Java
JavaScript is an Object-based Language Java is an object-oriented language.
There are also some similarities between JavaScript and java
like:
JavaScript and Java uses the same control flow statements
like if ....else, switch.... case construct; loop like while loop, do ...while
loop and for loop. Both languages follow the same syntax and rules to declare
names of variables, functions etc. to write programs and both are case
sensitive languages.
Objects
All things that exists in real world ranging from living to
non-living. We can touch and feel an object, like a human being or a chair
which are objects.
Method:
Methods are the properties of the objects. JavaScript can
manipulate behavior and actions of many objects. Document object's write()
method writes the text given within the parenthesis (" ") on the
document area.
Events
Browser executes web page line by line. We can change the
way in which the browser responds. For this purpose we use Events. Thus events
can be defined as those sets of links/codes by which sequence of execution
within a scripted program can controlled/altered. For instance, when a user
clicks a button, an event is generated which informs the browser about
occurrence of an action.
Variable
Variables can be defined as places/ spaces in the memory
storing data. Variables have names, which can use characters, digits and
underscore. There are some rules for naming variable.
- Spaces are not allowed.
- Punction character is not allowed.
- Variable name should start with a letter or underscore. Length can be of your choice
- Variable name are case sensitive(small letter or capital both are same).
The way to declare variable is
- Keyword var can be used, which is optional
- Assign value to the variable which you want.
Syntax
var x=1;
Data Types
Data type refers what types of data can be stored in a
particular variable. There are different type of data types in JavaScript. In
javascript we define data type before
the variable.
Number: It
includes both integers and floating - point number
String : Which includes one or more character of text
Boolean or Logical : These have two values true or
false
Null : Null value is a value which is undefined.
Program of JavaScript
<Script Language= “JavaScript”>
document.write(“Hello World”);
document.write(“<br>” + “=========”);
</Script>
Note: Script tag can be write with in <HTML> and
</Html> tag.
Example,
<html>
<head>
<Script Language= “JavaScript”>
document.write(“New Century Computer Point”);
document.write(“<br>”+ “====================”);
</Script>
</Head>
</Html>
- Write a program in JavaScript to print the sum of two numbers.
- Write a program to calculate simple Interest. Here (PV=5000, Rate=12%, Time=1)
Operators
Operators are the special
symbols which performs the calculating , comparison, etc. there are different types of operators
in JavaScript.
1.
Arithmetic Operators :
+ Addition
- Subtraction
* Multiply
/ Divide
% Modulation
(Reminder Value)
These operators can be used for
mathematical calculations. Generally there are two elements one is operator and
other is operand.
variables or constants are the
operand and symbols are the operators.
Example,
X + Y = Z
X, Y and Z are the operand .
+
and = are the operators.
2. Relational
Operators.
Relational operators mainly occur to compare two or more
then two values. There are two types of relational operators.
i.
Comparison Operator
> Greater than
< Less than
>= Greater than or equal to
< = Less than or Equal to
ii.
Equality Operator.
= = Equality
! = Not Equality
- Logical Operators
To show the true or false. There are mainly three types of
logical operators in JavaScript.
i. && Logical AND
Eg.
if(eng>=20 && mat
>=20)
{
document.write( "Pass");
}
else
else
{
document.write("Fail");
}
i. |
| Logical
OR
if(ans= = 'y' | | ans= = 'Y')
Alert("Good luck");
iii. ! logical
Not
Example,
while (x ! 0)
{
document.write("a");
}
- Unary operators
JavaScript supports very important two operators
increment and decrement. These operators are call unary operators.
+ + Increment
( increment by 1)
- - Decrement (Decrement by 1)
example,
x + + ; prefix
x= x+1;
+ + x ; Post fix
x=1+x;
x - - ; x=x-1
Control Statement
JavaScript is a object
based scripting Language. Doing programming, we need to control or execute the
required statement according to condition. There are different control
statements in JavaScript.
1.
Decision Making :
Decision making can be divide in two categories.
i
if else statement
if the given condition is true then
the true statement will execute(the statement before else), if the condition is
false then the false statement or statement after else will execute.
Syntax 1:
if(conditional expression)
{
statement;
statement;
}
else
{
statement;
statement;
}
1.
Write a program to print the greater number of the
given two numbers.
Syntax – 2
if(condition)
{
statement;
statement;
}
else if(condition)
{
statement;
statement;
}
else
{
statement;
statement;
}
Syntax: -3
if (conditional Expression)
{
if (Conditional _Expression)
{
statement1;
}
else
{
statement;
}
}
else if(conditional expression)
{
statement;
}
else
{
statement;
}
Example,
int x, y, z;
x=10;
y=22;
z=15;
if(x>y)
{
if(x>z)
{
document.write("X is
greatest");
}
else
{
document.write("Z is
greatest");
}
}
else if(y>z)
{
document.write("y is greatest");
}
else
{
document.write("Z is
greatest");
}
ii. Switch Case statement
The switch case statement is also
used for decision making. It always be used for multiple selection of the
options to run the particular statement. The use of this statement is that to
make menu.
Syntax:
switch (Expression)
{
case expression 1:
statement;
break;
case expression 2:
statement ;
break;
case expression 3:
statement;
break;
case expression 4:
statement;
break;
default:
statement;
break;
}
Note : Switch case statement takes two keywords, break and
default.
Break : to wait the
program on the screen.
default : Otherwise
to run false statement.
Example,
var day=1;
switch(day)
{
case 1:
document.write("Sunday");
break;
case 2:
document.write("Monday");
break;
...............
............
default:
document.write("Invild day");
break;
}
}
2. Looping
i.
For loop
It can be used to continue execute the program till the
given the condition is true. It takes the three statements. The first statement
for initial condition, second is stop condition and the third is increment or
decrement.
Syntax:
for(initial condition; last or stop condition; increment or
decrement)
{
statement;
}
e.g.
for(x=1;x<=10;x++)
{
document.write("<br>"+x);
}
ii.
While loop
It is also loop for the continue
the program.
Syntax:
while(condition)
{
statement;
statement;
}
E.g.
var x=1;
while(x<=10)
{
document.write("<br>"+x);
x=x+1;
}
iii. do while
loop
It can be used to continue execute the program till the
given condition will meet. It is also loop statement as while.
syntax:
syntax:
do
{
statement1;
statement2;
statement ...n;
}
while(conditional expression);
example,
int x=1;
do
{
document.write("<BR>"+x);
x=x+1;
}
while(x<=10);
- Write a program whether the given number odd or even.
- Write a program to print multiplication table of any number by using for loop, while loop, and do .. while loop.
- Write a program to print the fifonacci series ( 1,2,3,5,8,13,21…..) by using while and do while loop.
- Write a program to print the square number and cube number of 1 to 10.
- Write a program to print the number in descending order (10 to 1) by using for loop, while loop and do while loop .
Functions
Function are the building block of statements, which takes
some data, manipulate them and can return a value. Once a function has been
written and debugged, it can be used again and again from the other part of the
program. We can classify function in two groups. They are
- Function
- User defined functions.
- Functions: - Library functions are build-in functions. There are ready made commands in javascript.
for example, date(), getdate(),
sqrt() etc.
- User defined functions : - The functions which are made by the user.
Example,
<html>
<Head><title> function
in java</title>
</head>
<Script Language="JavaScript">
function hit()
{
document.write("<center>"+"Hello
world");
document.write("<br>
"+" =========");
}
function namrata()
{
document.write("<center>"+"Hi
Namrata");
document.write("<br>"+"==========");
}
</script>
<form>
<input type ="button"
name="dd" value="Hit" onClick="hit()">
<input type="button"
name="d" value="info" onClick="namrata()">
</form>
</html>
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