BY: SITI NURBAYA ISMAIL FACULTY of COMPUTER and MATHEMATICAL SCIENCES CSC317 – INTERNET PROGRAMMING CSC318 – DYNAMIC WEB APPLICATION DEVELOPMENT BY: SITI NURBAYA ISMAIL FACULTY of COMPUTER and MATHEMATICAL SCIENCES

Outline Basic JavaScript Syntax (recap) Variable (recap) JavaScript Functions (recap) Parsing User Input (recap) Logical structures How to Process Inputs Form Validation Page 2

Basic JavaScript Comparison Operators (the following examples will used x = 5) Operator Description Example == is equal to x == 8 is false === is exactly equal to (value and type) x === 5 is true x === “5” is false != is not equal to x != 8 is true > is greater than x > 8 is false < is less than x < 8 is true <= is less than or equal to x <= 8 is true >= is greater than or equal to x >= 8 is false Page 3

Basic JavaScript Logical Operators determine logic between values (the following examples will used x = 6 and y = 3) Operator Description Example && and (x < 10 && y > 1) is true || or (x == 5 || y == 5) is false ! not !(x == y) is true Page 4

Basic JavaScript Logical Structures Your application may involves conditions Example If male, he wears “baju melayu” If female, she wears “baju kurung” JavaScript has logical structures (conditional statements), where you need to use operators on the previous two slides Page 5

Basic JavaScript Conditional Statements Used to perform different actions based on different conditions/decisions if statement execute some code only if a specified condition is true if..else statement execute some code if the condition is true and another code if the condition is false if..else if...else statement select one of many blocks of code to be executed switch statement Page 6

Basic JavaScript Logical Structures Simple examples if(male){ document.write(“He wears baju melayu”); } else{ document.write(“She wears baju kurung”); switch(gender){ case “male” : case “MALE”: alert(“He wears baju melayu”); break; case “female”: alert(“She wears baju kurung”); default : alert(“Please select gender!”); } Page 7

Basic JavaScript Logical Structures if statement: execute some code if a specified condition is true if(condition){ // execute the code if condition is true } if(place == “Merbok”){ document.write(“It is situated in Kedah”); } if(university == “UiTM” && place == “Merbok”){ document.write(“It is situated in Kedah”); } Page 8

Basic JavaScript Logical Structures if statement: execute some code if a specified condition is true if(program == “CS113” || program == “CS110”){ document.write(“These are UiTM programs”); } if(time >= 1 && time < 12){ document.write(“Good Morning!”); } Page 9

Basic JavaScript Logical Structures if…else statement: execute some code if a specified condition is true, and another code if the condition is false if(condition){ // execute the code if condition is true } else{ // execute the code if condition is false Page 10

Basic JavaScript Logical Structures if…else statement: execute some code if a specified condition is true, and another code if the condition is false if(gender == “Male”){ document.write(“Go to Hall A”); } else{ document.write(“Go to Hall B”); Page 11

Basic JavaScript Logical Structures if…else if…else statement: use this statement if you want to select one of many blocks of code to be executed if(condition1){ // execute code if condition1 is true } else if(condition2){ // execute code if condition2 is true else if(condition3){ // execute code if condition3 is true else{ // execute code if all conditions are false Page 12

Basic JavaScript Logical Structures if…else if…else statement: use this statement if you want to select one of many blocks of code to be executed if(program == “AS120”){ document.write(“Diploma in Science”); } else if(program == “CS110”){ document.write(“Diploma in Computer Science”); else if(program == “AC110”){ document.write(“Diploma in Accountancy”); else{ document.write(“Please select program code”); Page 13

Basic JavaScript Logical Structures switch() statement: use this statement if you want to select one of many blocks of code to be executed switch(var){ case 1: // execute code block 1 break; case 2: // execute code block 2 break; // break the loop and continue executing the code that follows after the loop (if any). default: //execute code if var is different // from case 1, 2, 3 } Page 14

Basic JavaScript Logical Structures switch() statement example: switch(month){ case 1: document.write(“January”); break; case 2: document.write(“February”); case 3: document.write(“March”); default: document.write(“None of the above”); } Page 15

Basic JavaScript How to Process Inputs 1 input field, which a text field, name num1 1 input field, which a text field, name num2 1 drop down list, name operator 1 Submit button Supposedly, if user input value within the input fields and select a value in the dropdown list, then click the Submit button, the value from num1 & num2 will be processed create an event that will call a JavaScript function first that event can be placed at the Submit button Page 16

Basic JavaScript How to Process Inputs Create a complete HTML form with several input fields [ Your previous coding in Question 5 ] Page 17

Basic JavaScript How to Process Inputs Now, we create the JavaScript user-defined function first, which will be placed at <head>…</head> tag Every time you create user-defined function, it must starts with function followed by function_name, brackets (()), and braces ({}) For this example, create a function name kira() <script type=“text/javascript”> function kira(){ // your JavaScript code is here } </script> Page 18

Basic JavaScript How to Process Inputs To capture value or data from input field, we have to write this code Now, place the code above in the kira(), where it would be like this var fname = document.{form_name}.{field_name}.value; var num1 = document.f1.num1.value; var num2 = document.f1.num2.value; var operator = document.f1.operator.value; Page 19

Basic JavaScript How to Process Inputs <script type="text/javascript"> function kira(){ var num1 = document.f1.num1.value; var num2 = document.f1.num2.value; var operator = document.f1.operator.value; } </script> Now, add onclick event on the Submit button to call kira() <input type=“button" name="submit" value="Submit" onclick=“kira()"> Page 20

Page 21

Basic JavaScript How to Process Inputs We can also validate/check numeric input using isNaN() Now, add this code in function kira() before after calling the input from form f1. Page 22

Page 23

Basic JavaScript How to Process Inputs Create a complete HTML form with several input fields [ Your previous coding in Question 3 ] Using JavaScript codes, retrieve height and weight values from HTML form. Next, proceed with BMI calculation and determine the category of BMI according to BMI value. Category BMI range – kg/m² Starvation Less than 14.9 Underweight From 15 to 18.4 Normal From 18.5 to 22.9 Overweight From 23 to 27.5 Obese From 27.6 to 40 Morbidly obese Greater than 40 Your BMI is 19.53 and you are Normal Page 24

Based on figure below, create a JavaScript function that able to check your grade according to your mark. Your JavaScript function must be able to accept an input from HTML form, which enters by user. Next, user will click on Check Grade button to check his/her grade. Display the grade in the text field in HTML form. Please follow conditions in the Table 1, in order to check the grade. Table 1 Marks Grade & Status 90 – 100 A+ 80 – 89 A 75 – 79 B+ 70 – 74 B 65 – 69 B- 60 – 64 C+ 55 – 59 C 0 – 54 Please work harder Page 25

Basic JavaScript How to Process Inputs Write the JavaScript codes for each of the following: An increment of salary for UPeM lectures based on the following table: Write a complete JavaScript program to calculate and didplay a new salary for UPeM lecturers using an alert box. A program should prompt the user to enter basic salary and grade. Please notify user if they enter invalid grade. Define the calcNewSal() function to calculate the new salary where the function will receives salary increment and increment percentage an return a new salary. Grade PERCENT OF INCREMENT A 20% B 25% C 35% Page 26

Basic JavaScript How to Process Inputs Write the JavaScript codes for the following question: A switch statement that, given a number representing a TV channel, it displays the name of the station that corresponds to that number, or displays some message indicating that the channel is not used. Capture the input using prompt box and output the result using alert box. Use the following channel numbers and the station names: 102:TV2 104:Astro Ria 105:Astro Prima 107:NTV7 114:TVAIHijrah 305:TVB Classic Channel Page 27

Form Enhancement Eror Checking Why we have to perform error checking / input verification? To avoid any (unnecesary|invalid) (character|input) from being accepted according to defined (pattern|format) Sometimes, each input has its own pattern or format that will determine that input is valid or invalid Examples: Email address verification Name verification Phone number verification Page 28

Form Enhancement Eror Checking Write a JavaScript function name checkPassword() that will check passwords entered by user and display status of the passwords. Please refer to Figure 3 for your interface : Page 29

Form Enhancement Eror Checking no value being entered, undefined value, numeric value <html> <head> <script type="text/javascript"> function cap(){ var fname = document.f1.fname.value; alert("Name: " + fname); } </script> </head> <body> <form name="f1"> Name: <input type="text" name="fname"> <input type=“button“ value="Submit" onclick=“cap()"> </form> </body> </html> Page 30

Form Enhancement Eror Checking no value being entered, undefined value, numeric value cap() 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 cap() accept the value without need to do error checking? What will happen if user does not enter any value? The field leave blank <script type="text/javascript"> function cap(){ var fname = document.f1.fname.value; alert("Name: " + fname); } </script> Page 31

Form Enhancement Eror Checking no value being entered, undefined value, numeric value <script type="text/javascript"> function cap(){ var fname = document.f1.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 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> Page 32

Form Enhancement Eror Checking fname = ″″ and fname = null are two different statements fname = ″″ fname = null check if the value is empty check if the value is null (undefined or unknown) Page 33

Form Enhancement Eror Checking Required Field The function below checks if a field has been left empty. If the field is blank, an alert box alerts a message, the function returns false, and the form will not be submitted: <html> <head> <script> function validateForm() { var x=document.forms.myForm.fname.value; if (x==null || x=="") alert("First name must be filled out"); return false; } </script> </head> <body> <form name="myForm" action="demo_form.asp" onsubmit="return validateForm()" method="post"> First name: <input type="text" name="fname"> <input type="submit" value="Submit"> </form> </body> </html> Page 34 http://www.w3schools.com/js/js_form_validation.asp

Form Enhancement Eror Checking E-mail Validation The function below checks if the content has the general syntax of an email. This means that the input data must contain an @ sign and at least one dot (.). Also, the @ must not be the first character of the email address, and the last dot must be present after the @ sign, and minimum 2 characters before the end: <html> <head> <script> function validateForm() { var x=document.forms.myForm.email.value; var atpos=x.indexOf("@"); var dotpos=x.lastIndexOf("."); if (atpos<1 || dotpos<atpos+2 || dotpos+2>=x.length) alert("Not a valid e-mail address"); return false; } </script> </head> <body> <form name="myForm" action=“" onsubmit="return validateForm()" method="post"> Email: <input type="text" name="email"> <input type="submit" value="Submit"> </form></body></html> Page 35 http://www.w3schools.com/js/js_form_validation.asp

Introduction to Client-Side Scripting Bibliography (Book) Knuckles (2001). Introduction to Interactive Programming on the Internet using HTML & Javascript. John Wiley & Sons, Inc. Bibliography (Websites) http://www.w3schools.com/js/default.asp http://www.w3schools.com/js/js_form_validation.asp http://webcheatsheet.com/javascript/form_validation.php Page 36 36