Computer Science Students: III Bcom

Q) What is DHTML? What are the features of DHTML?

DHTML stands for Dynamic HTML. DHTML is neither a language like HTML, JavaScript etc. nor a web standard. It is just a combination of HTML, JavaScript and CSS. It just uses these languages features to build dynamic web pages. DHTML is a feature of Netscape Communicator 4.0, and Microsoft Internet Explorer 4.0 and 5.0 and is entirely a "client-side" technology.

Features of DHTML:

1. Simplest feature is making the page dynamic.
2. Can be used to create animations, games, applications, provide new ways of navigating through web sites.
3. DHTML use low-bandwidth effect which enhance web page functionality.
4. Dynamic building of web pages is simple as no plug-in is required.
5. Facilitates the usage of events, methods and properties and code reuse

Q) Write a brief note on JavaScript?

JavaScript was developed by Netscape (company name) & initially called Livescript. Later Microsoft developed and adds some futures Live script then it is called “Jscript”. Jscript is nothing but Java script. We cannot create own classes in java script.

Java script is designed to add interactivity to HTML pages. It is usually embedded directly into html pages.

Java script is mainly useful to improve designs of WebPages, validate from data at client side, detects (find) visitor’s browsers, create and use to cookies, and much more.

Java script is also called light weight programming language, because Java `script is return with very simple syntax. Java script is containing executable code.

Java script is also called interpreted language, because script code can be executed without preliminary compilation.

Creating a java script: - html script tag is used to script code inside the html page.

The script is containing 2 attributes. They are

1) Language attribute: - It represents name of scripting language such as JavaScript, VbScript.

2) Type attribute: - It indicates MIME (multi purpose internet mail extension) type of scripting code. It sets to an alpha-numeric MIME type of code.

Location of script or placing the script: - Script code can be placed in both head & body section of html page.

Script in head section Script in body section

Script code here </script>

</script> </head>

</head> <body>

<body> Script code here

</body> </body>

</html> </html>

Scripting in both head & body section: - we can create unlimited number of scripts inside the same page. So we can locate multiple scripts in both head & body section of page.

Ex: -

<html>

<head>

Script code here

</script>

</head>

<body>

Script code here

</script>

</body>

</html>

Program: -

<html>

<head>

document.write("hai my name is Mahaboob Shaik")

</script>

</head>

document.write("hai my name is Sunil Kumar Reddy")

</script> </marquee>

</body>

</html>

Q) What is a variable? How to declare a variable in javascript.

Declaring variable: - variable is a memory location where data can be stored. In java script variables with any type of data are declared by using the keyword ‘var’. All keywords are small letters only.

var a; a=20;

var str; str= “Sunil”;

var c; c=’a’;

var d; d=30.7;

Explain different types of operators in Javascript.

Operators: - when ever you combined operators & operands then it is called operation. There are 3 types of operators.

Unary operator: - if operator acts upon single operand then it I called unary operator.

Binary operator: -if operator acts upon two operands then it I called binary operator.

Ternary operator: - if operator acts upon three operands then it I called ternary operator

1) Arithmetic operators: - + , - , * , / , % , ++ , --

a=20;

- a; // - operator act upon only single operand, so it is called unary operator.

a=20;

b=40;

a - b; // - operator act upon only single operand, so it is called binary operator.

*, / , % à pure binary operators.

2) Assignment operators: -

= is 1^st category à it assigns variables.

+ = , - = , * = , / = , % = à 2^nd category.

These sets of operators are compound assignment operators & combine couple of the statements.

a = a + b; a+=b; // both are same.

3) Relational operators: - < , > , > = , < = , = =

! = = , = = = , ! = = = (newly defined)

When you compare two quantities, we can use relational operators.

*Ex: -

a=20;

b=“20”;

a==bà returns true

a===b à returns false.

Because = = checks only content of variable, = = = checks both data & type of data of variable in java script.

4) Logical operators: - && , || , !

Compare two or more quantities we can use logical operators. These operators are just like boolean (true / false)

((cond1)&&(cond2)&&(cond3))

All conditions must be true it is true otherwise false.

((cond1)||(cond2)||(cond3))

Any one condition is true it is true otherwise false.

5) Conditional operators: - : , ?

var1=(cond)?var2:var3

Ex: - a=20; b=30;

big=(a>b)?a:b

document.write(big)

6) New operator: - new operator is creating one object dynamically.

var obj=new classname( )

Ex: - var d=new Date( );

d.getMonth( );

Q) Give a brief note on Conditional statements in Javascript.

Conditional statements: -

In Java Script conditional statements are useful to excuse different action for different decisions (conditions).

if statement.

if-else statement.

switch statement.

if statement is useful to perform(execute) a single statement or group of statements when the condition is true.

if – else statement is useful to execute a one block of code from two blocks where one condition.

Switch statement is very frequently to select one of many blocks of code for execution.

Ex: -

<HTML>

<BODY>

var d=new Date( );

var day=d.getDay( );

switch(day)

{

case 0:

document.write("enjoy Sunday");

break;

case 1:

document.write("learning Monday");

break;

case 2:

document.write("popper Tuesday");

break;

case 3:

document.write("middle Wednesday");

break;

case 4:

document.write("temple Thursday");

break;

case 5:

document.write("finally Friday");

break;

case 5:

document.write("super Saturday");

break;

default :

document.write("I am looking forward for this week end");

}

</script>

</BODY>

</HTML>

O/P: - learning Monday

Q) Explain different types of loops in Javascript.

Control structures :-( loops)

In java script loops are useful to perform one block of code repeatedly for specified no of times. There are 3 types of loops.

while loop

do-while loop

for loop.

1) while loop:- while loop is useful to execute a block of code repeatedly bussed on condition. It is also entry controlled loop.

Syntax: - while(cond) { --- }

Ex: - <HTML>

<HEAD>

<TITLE> Natural No's up to 100 using while </TITLE>

</HEAD>

<BODY>

a=1;

while(a<=100)

{

document.write(a+" ");

a++;

}

</script>

</BODY>

</HTML>

O/P: - 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100

2) do-while loop: - do-while loop is useful to execute a block of code repeatedly based on condition. It is also called exit controlled loop.

Syntax: - do { --- } while(cond);

Ex: - <HTML>

<HEAD>

<TITLE> Fibonacci series up to 10 </TITLE>

</HEAD>

<BODY>

a=0;

b=1;

document.write( a+" "+b+" ")

c=2;

{

s=a+b;

document.write( s+" ");

c++;

a=b;

b=s;

}

while (c<10);

</script>

</BODY>

</HTML>

O/P: - 0 1 1 2 3 5 8 13 21 34

3) for loop: -

Syntax: - for(initialization; cond; (inc / dec)) { ------ }

Ex: - <HTML>

<HEAD>

<TITLE> Prime no's up to 100 </TITLE>

</HEAD>

<BODY>

for(i=0;i<=100;i++)

{

c=0;

for(j=0;j<=i;j++)

{

if(i%j==0)

c++;

}

if(c==2)

document.write( i+" ");

}

</script>

</BODY>

</HTML>

O/P: - 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Computer Science Students

Wednesday, 1 August 2018

III Bcom

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