Web Application Development Muhammad Ali Versonic Pte Asher Imtiaz Forman Christian College

 The Problem  Changing the Content of Page Dynamically  Efficient Utilization of Resources

 The Solution  How?  Scripting Languages

 Interpreted Languages  Purpose  “Automate tasks within a particular software environment”  JavaScript  VBScript  JScript

 Case Sensitive  X != x  Few Snapshots from History  Developed by Brendan Eich (Netscape 2.0)  How the Name was Coined? ▪ LiveScript ▪ Renamed to JavaScript (Dec 1995 ) ▪ Marketing Tactics ▪ Similarity with Java (& C++)  Standardization Efforts ▪ ECMAScript

Communication XHTMLCSS JavaScript Flash Java Silverlight

Communication HTMLCSS JavaScript Flash Silverlight Java

Communication HTMLCSS JavaScript Flash Silverlight Java

Communication HTMLCSS JavaScript Flash Silverlight Java

Communication HTMLCSS JavaScript Flash Silverlight Java

 How to add JavaScript?  &  Inclusion Methods ▪ Same File (HTML File) ▪ External File (JS File) ~ Preferred Approach

alert("Hello World!");

alert("Hello World!"); Please enable JavaScript!

<!-- alert("Hello World!"); // --> Please enable JavaScript!

 alert  prompt  confirm

 Number  1  2.3  String  “a string”  Boolean  true  false

 Name it and Have it!  Use ‘var’ to declare variables!  Examples var num1 = 1; var num2 = 2.3; var str = “A String”; var anyVar; // undefined

 String Type  To append to strings var str1 = “abc”; var str2 = “def”; var strResult = str1 + str2;  What about var result = “1” + 2; And var result = “1” - 2; And var someVar ; // No initialization alert(someVar);

 Boolean Type  false ▪ false, undefined, null, 0, NaN, “” (empty string)  true ▪ Any other value is considered as true ▪ true, “abc”, 1, …

 alert(typeof (1));  number  alert(typeof(“abc”));  alert(typeof(“1”));  alert(typeof(true));

 parseInt  Converts a string to an integer number var integerNumber = parseInt(“12”);  parseFloat  Converts a string to a float number var floatNumber = parseFloat(“12.12”);  Converting a Number to a String?

 Loops  For Loop for (start; stop; step) { action } Example for (var i = 0 ; i < 10 ; ++i) { alert(i); }

 While Loop boolean someCondition = true; while (someCondition) { // Do something }

 Do-While Loop boolean someCondition = true; do { // Do something } while (someCondition);

Different forms  if (expr) { // Do something }

 if (expr) { // Do something } else { // Do something }

if (expr) { // Do something } else if (expr) { // Do something } else { // Do something }

switch (expr) { case value1: break; case value2: break; case valueN: break; default: break; } switch (grade) { case “A”: break; case “B”: break; case “C”: break; default: break; }

 Objects ▪ “An object in JavaScript is a set of properties, each of which consists of a unique name and a value belonging to one of JavaScript’s six data types” ▪ NO Classes in JavaScript! ▪ Class-Like features. var obj = new Object(); obj.Test = “Some Value”; alert(obj.Test); // Some Value delete obj.Test; alert(obj.Test); // undefined

 Enumerating Properties for (var aProperty in obj) { alert(aProperty + “ is a property of obj”); }  Displays Test is a property of obj

 Accessing Properties  obj[“Test”] = “someValue”; for (var aProperty in obj) { alert(aProperty + “ has value:” + obj[aProperty]); }

var str = new String(“This is a string”); var str = new String("abcdef"); var ch = str.charAt( 0 ); var index = str.indexOf("b", 0 ); if (index > 0 ) alert("Found at index: " + index); else alert("Not Found!");

 split(separater, limit)  toLowerCase()  toUpperCase()

 What’s an Array?  var ar1 = new Array();  var ar1 = new Array(5);  var ar2 = new Array(4, true, “OK”);  var ar3 = [4, true, “OK”];  var twoDimAr = [ [ “X”, “O”, “O”], [ “O”, “X”, “O”], [ “O”, “X”, “O”] ];

 Access an Element at Index ‘i’  ar[i] = 12;  alert(ar[3]);

 toString  splice  reverse  length  push

 Math  abs, ceil, floor, round, random, …  Trigonometric, logarithmic, etc  Date  Dates before January 1, 1970 are not supported

 What have we learnt today?  Need for client side programming  Why scripting languages?  JavaScript for client side programming  Language features of JavaScript