CSC317 – INTERNET PROGRAMMING CSC318 – DYNAMIC WEB APPLICATION DEVELOPMENT

CSC317 – INTERNET PROGRAMMINGCSC318 – DYNAMIC WEB APPLICATION DEVELOPMENTBY: SITI NURBAYA ISMAILFACULTY of COMPUTER and MATHEMATICAL SCIENCES

Outline

For Loop While Loop Do While Loop User-defined Function Error Checking Working with Web Pages Properties

Basic JavaScript

Basic JavaScript

Execute the same block of code according specified times

for Loop

for(var = startValue; var <= endValue; var = var + increment){// execute the block code until var = endValue

}

var x;for(x = 0; x <= 10; x++){

document.write(“Number: ” + x + “<br>”);}

Basic JavaScript

Another example on for loop

for Loop

var x;var msg = “I promise I won’t be disturb people again.”;for(x = 1; x <= 1000; x++){

document.write(msg + “<br>”);}

Basic JavaScript

Execute the same block of code while a specific condition is true

while Loop

while(var <= endValue){// execute the code

}

var x = 0;while(x <= 10){

document.write(“Number: ” + x + “<br>”);x++; // x = x + 1

}

Basic JavaScript

Another example on while loop

while Loop

var month_name, month = 1;while(month <= 3){

if(month == 1){month_name = “January”;

}else if(month == 2){

month_name = “February”;}else if(month == 3){

month_name = “March”;}else{

alert(“Please select month!”);}month = month + 1;

}

Basic JavaScript

Execute the block of code at least once even the condition is false, because the code will be executed first before condition is tested. It will repeat the loop as long as the specified condition is true.

do...while Loop

var x = 0;do{

document.write(“Number is: ” + x + “<br>”);x = x + 1;

}while(x < 0)

do{// execute the code

}while(var <= endValue)

Basic JavaScript

Write a JavaScript code that will generate similar output in Figure 1. Please use for loop.

Question 1: for Loop

Figure 1

Basic JavaScript

Write a JavaScript code that will generate similar output in Figure 2. Please use for loop.


Figure 2

*calculate the value within your loop

Basic JavaScript

A function created by user to perform specific task

User-defined Function

<html><head><script type="text/javascript">function myFunction(){

var msg = "Hello World!";return (msg);

}</script></head><body><script type="text/javascript">document.write(myFunction());</script></body></html>

Basic JavaScriptUser-defined Function

<script language="javascript“>function kira(){ var num1=parseFloat(document.f1.num1.value); var num2=parseFloat(document.f1.num2.value); var operator=document.f1.operator.value; var sum;

if(operator=="add"){ sum=num1+num2; } else if(operator=="minus"){ sum=num1-num2; } else if(operator=="multiple"){ sum=num1*num2; } else if(operator=="division"){ sum=num1/num2; } else{ alert("select an operator"); } document.f1.result.value=sum;}</script>

function xx(){}

Basic JavaScriptUser-defined Function

return Statement The return statement is

used to specify the value that is returned from the function.

So, functions that are going to return a value must use the return statement.

The example below returns the product of two numbers (a and b):

Example

<html><head><script type="text/javascript">function product(a,b){return a*b;}</script></head><body><script type="text/javascript">document.write(product(4,3));</script></body></html>

Basic JavaScript

Remember this example?

Error Checking

<html><head><script type="text/javascript">function myFunction(){

var fname = document.form1.fname.value;alert("Name: " + fname);

}</script></head><body><form name="form1">Name: <input type="text" name="fname"><input type="submit" name="submit" value="Submit" onclick="myFunction()"></form></body></html>

Basic JavaScript

myFunction() will capture a value from fname text field. This field is specifically for people´s name, which is string value

What will happen if user enter numeric value?- Should myFunction() accept the value without need to do error checking?

What will happen if user does not enter any value? The field leave blank

Error Checking

<script type="text/javascript">function myFunction(){

var fname = document.form1.fname.value;alert("Name: " + fname);

}</script>

Basic JavaScriptError Checking

<script type="text/javascript">function myFunction(){

var fname = document.form1.fname.value;if(fname == ""){ // check if no value being entered

alert("Please enter a name!");}else if(fname == null){ // check if there is undefined value

alert("Please enter a name!");}else if(!isNaN(fname)){ // check if value is numeric

alert("Invalid character. Name must be alphabet.");}else{ // all conditions above false

document.write("Name: " + fname);}

}</script>

Basic JavaScript

fname = ″″ and fname = null are two different statements fname = ″″ : check if the value is empty fname = null : check if the value is null (undefined or unknown)

Error Checking

Basic JavaScript

Write a JavaScript code that will generate similar output in Figure 3. • Within your form

• A text field for user input• A button to trigger a function

• to check the input as numeric input• to generate times calculation based on the input• the calculation will start from 1 until 12.• output a list of the times calculation

(you can used two for loop in your coding)• A button to reset the value


Basic JavaScript

Write a JavaScript code that will generate similar output in Figure 43. • Within your form

• A text field for user input• set maximum length of user input as 2 value

• A button to trigger a function • to check the input as numeric input• to check the input either odd or even• output a list of different odd and even number .

(you can used two for loop in your coding)• A button to reset the value


Basic JavaScript


Figure 3

Basic JavaScript

May be you are not realized that you have used Web Pages properties (or Document properties) a few times

Example:- document.write(): to display information on the web page

We have others like:- document.bgColor- document.fgColor- document.lastModified

Working with Web Pages Properties

<html><head><title>document.bgcolor</title></head>

<body bgcolor="beige" text= "black" link="darkblue" vlink="honeydew">

<script language="javascript">

document.write("the background color is "+document.bgcolor+"<br>");

</script>

</body>

</html>

Basic JavaScriptWorking with Web Pages Propertiesdocument.bgColor

<html>

<head><script language="JavaScript"> function changeBG(color) { document.bgColor=color; //Change background color document.f1.color.value=color; //Display the color }</script></head>

<body>

<form name="f1"> <input type="button" value="OceanBlue" name="Yellow" onClick="changeBG('#94FFFF')"> <input type="button" value="LimeGreen" name="Green" onClick="changeBG('#B8FF94')"> <input type="text" name="color"></form>

</body></html>

Basic JavaScriptWorking with Web Pages Propertiesdocument.bgColor

<html><head><title>document.fgcolor</title></head>

<body bgcolor="beige" text="red" link="darkblue" vlink="honeydew">

<script language="javascript">

document.write("the text color is "+document.fgcolor+"<br>");

</script>

</body>

</html>

Basic JavaScriptWorking with Web Pages Propertiesdocument.fgColor

<html><head><title>document.lastModified</title></head>

<body>

This document was last modified on:

<script type="text/javascript">

document.write(document.lastModified);

</script>

</body>

</html>

Basic JavaScriptWorking with Web Pages Propertiesdocument.lastModified

Knuckles (2001). Introduction to Interactive Programming on the Internet using HTML & Javascript. John Wiley & Sons, Inc.

http://www.w3schools.com/js/default.asp

Bibliography (Book)

Bibliography (Website)

http://www.w3schools.com/js/default.asp

CSC317 – INTERNET PROGRAMMING CSC318 – DYNAMIC WEB APPLICATION DEVELOPMENT

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