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JavaScript
Introduction
1
JavaScriptIntroduction
What is Java Script ?
• JavaScript is a client-side scripting language.
• A scripting language is a lightweight programmin...
What is Java Script ?
• JavaScript is used in Web site development to such
things as:
 check or modify the contents of fo...
Java Script Vs Java
JavaScript Java
Interpreted (not compiled)
by client.
Compiled on server before
execution on client.
O...
ECMA Script
• The responsibility for the development of a
scripting standard has been transferred to an
international body...
Writing a Java Script Program
• The Web browser runs a JavaScript program
when the Web page is first loaded, or in
respons...
Writing a Java Script Program
• A JavaScript program can be placed
anywhere within the HTML file.
• Many programmers favor...
How to use/implement Java Script?
• We can implement Java script in our web
page by following three ways-
1. Inside the he...
Implementing Java Script
1. Inside HEAD Tag:
Syntax:
<HTML>
<HEAD>
<SCRIPT TYPE= “TEXT/JAVASCRIPT”>
<!- -
Java Script Code...
Implementing Java Script
2. Within BODY Tag:
Syntax:
<HTML>
<HEAD>
</HEAD>
<BODY>
<SCRIPT TYPE= “TEXT/JAVASCRIPT”>
<!- -
j...
Implementing Java Script
3. In an External Link:
Syntax:
<HTML>
<HEAD>
<SCRIPT SRC= “myscript.js”>
</SCRIPT>
</HEAD>
<BODY...
Java Script Syntax Issue
• JavaScript commands and names are case
sensitive.
• JavaScript command lines end with a
semicol...
Displaying some text on web Page
• You can write on page by using following
statement of Java script-
document.write(“mess...
JavaScript Display Possibilities
• JavaScript does NOT have any built-in print or
display functions.
• JavaScript can "dis...
window.alert()
<!DOCTYPE html>
<html>
<body>
<h1>My First Web Page</h1>
<p>My first paragraph.</p>
<script>
window.alert(5...
16
JavaScriptIntroduction
document.write()
<html>
<body>
<h1>My First Web Page</h1>
<p>My first paragraph.</p>
<button type="button"
onclick="docume...
18
JavaScriptIntroduction
innerHTML
<html> <body>
<h1>My First Web Page</h1>
<p>My First Paragraph.</p>
<p id="demo"></p>
<script>
document.getEleme...
20
JavaScriptIntroduction
console.log()
<!DOCTYPE html>
<html><body>
<h1>My First Web Page</h1>
<p>My first paragraph.</p>
<p> Activate debugging in...
22
JavaScriptIntroduction
Working with Variables & Data
• A variable is a named element in a program
that stores information.
var var_name;
• The fo...
Types of Variables
• JavaScript supports four different types
of variables
•Numeric variables can be a number, such
as 13,...
Declaring/Creating a Variable
• Before you can use a variable in your
program, you need to declare a variable
using the va...
Operators in JavaScript
• Following operators are used in
JavaScript-
1. Arithmetic Operator
2. Comparison Operator
26
Jav...
Operators in JavaScript
• Following operators are used in JavaScript-
1. Arithmetic Operator
Operator Meaning Example
+ Ad...
Example
<body>
<script
type="text/JavaScript">
<!–
var two = 2
var ten = 10
var linebreak = "<br />"
document.write("two p...
Output
two plus ten = 12
ten * ten = 100
ten / two = 5
29
JavaScriptIntroduction
Operators in JavaScript
2. Comparison Operator
Operator Meaning Example Result
== Equal To x == y false
=== Equal value an...
Built-in JavaScript Functions
• Functions provided by the language and you cannot
change them to suit your needs.
• Some o...
JavaScript Functions
• A function is a block of organized reusable
code (a set of statements) for performing a
single or r...
Creating JavaScript Functions
Declaration Syntax
• Functions are declared using the function
reserved word
• The return va...
Creating JavaScript Functions: Eg
<HTML>
<HEAD>
<SCRIPT TYPE=TEXT/JAVASCRIPT>
<!- -
function myMessage()
{
document.write(...
Event in JavaScript
• JavaScript is its ability to help you create dynamic web
pages that increase user interaction
• The ...
Event in JavaScript
• JS Event Handler
• Onclick
• onMouseOver
• onMouseOut
• onLoad
• onkeydown
36
JavaScriptIntroduction
JavaScript Object
• Object
• Number
• String
• Date
• Array
• Boolean
• Math, etc
37
JavaScriptIntroduction
What is the DOM?
• The DOM is a W3C (World Wide Web Consortium)
standard.
• The DOM defines a standard for accessing docum...
What is the HTML DOM?
• The HTML DOM is a standard object model and
programming interface for HTML.
• It defines:
• The HT...
• When a web page is loaded, the browser creates a Document
Object Model of the page.
• The HTML DOM model is constructed ...
• With the object model, JavaScript gets all the power it
needs to create dynamic HTML:
• JavaScript can change all the HT...
The HTML DOM Document
• HTML DOM object model, the document object
represents your web page.
• The document object is the ...
Finding HTML Elements
JavaScriptIntroduction
43
Method Description
document.getElementById() Find an element by element id...
Changing HTML Elements
JavaScriptIntroduction
44
Method Description
element.innerHTML= Change the inner HTML of an element...
Adding and Deleting Elements
JavaScriptIntroduction
45
Method Description
document.createElement() Create an HTML element
...
Adding Events Handlers
JavaScriptIntroduction
46
Method Description
document.getElementById(id).
onclick=function()
{code}...
Document Object
• Java script enable browsers are capable of recognizing
individual objects in a HTML page.
• Each HTML do...
Validation in JavaScript
48
JavaScriptIntroduction
<!DOCTYPE html><html><body>
<h1>JavaScript Can Validate Input</h1>
<p>P...
JavaScriptIntroduction
49
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Java script

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Java script

  1. 1. JavaScript Introduction 1 JavaScriptIntroduction
  2. 2. What is Java Script ? • JavaScript is a client-side scripting language. • A scripting language is a lightweight programming language. • JavaScript is programming code that can be inserted into HTML pages. • JavaScript inserted into HTML pages, can be executed by all modern web browsers. • Java Script can enhance the dynamics and interactive features of your page by allowing you to perform calculations, check forms, write interactive games, add special effects, customize graphics selections, create security passwords and more. 2 JavaScriptIntroduction
  3. 3. What is Java Script ? • JavaScript is used in Web site development to such things as:  check or modify the contents of forms  change images  open new windows and write dynamic page content.  to make DHTML by CSS.  This allows you to make parts of your web pages appear or disappear or move around on the page 3 JavaScriptIntroduction
  4. 4. Java Script Vs Java JavaScript Java Interpreted (not compiled) by client. Compiled on server before execution on client. Object-based. Code uses built-in, extensible objects, but no classes or inheritance. Object-oriented. Applets consist of object classes with inheritance. Code integrated with, and embedded in, HTML. Applets distinct from HTML (accessed from HTML pages). Variable data types not declared (loose typing). Variable data types must be declared (strong typing). Secure. Cannot write to hard disk. Secure. Cannot write to hard disk. 4 JavaScriptIntroduction
  5. 5. ECMA Script • The responsibility for the development of a scripting standard has been transferred to an international body called the European Computer Manufacturers Association (ECMA). • The standard developed by the ECMA is called ECMAScript, though browsers still refer to it as JavaScript. • The latest version is ECMA-262, which is supported by the major browsers. 5 JavaScriptIntroduction
  6. 6. Writing a Java Script Program • The Web browser runs a JavaScript program when the Web page is first loaded, or in response to an event. • JavaScript programs can either be placed directly into the HTML file or they can be saved in external files. • placing a program in an external file allows you to hide the program code from the user • source code placed directly in the HTML file can be viewed by anyone 6 JavaScriptIntroduction
  7. 7. Writing a Java Script Program • A JavaScript program can be placed anywhere within the HTML file. • Many programmers favor placing their programs between <head> tags in order to separate the programming code from the Web page content and layout. • Some programmers prefer placing programs within the <Body> of the Web page at the location where the program output is generated and displayed. 7 JavaScriptIntroduction
  8. 8. How to use/implement Java Script? • We can implement Java script in our web page by following three ways- 1. Inside the head tag 2. Within the body tag 3. In an external file (with extension .js) 8 JavaScriptIntroduction
  9. 9. Implementing Java Script 1. Inside HEAD Tag: Syntax: <HTML> <HEAD> <SCRIPT TYPE= “TEXT/JAVASCRIPT”> <!- - Java Script Code // - -> </SCRIPT> </HEAD> <BODY> </BODY> </HTML> 9 JavaScriptIntroduction
  10. 10. Implementing Java Script 2. Within BODY Tag: Syntax: <HTML> <HEAD> </HEAD> <BODY> <SCRIPT TYPE= “TEXT/JAVASCRIPT”> <!- - java script code // - -> </SCRIPT> </BODY> </HTML> 10 JavaScriptIntroduction
  11. 11. Implementing Java Script 3. In an External Link: Syntax: <HTML> <HEAD> <SCRIPT SRC= “myscript.js”> </SCRIPT> </HEAD> <BODY> <input TYPE=“Button” onclick=“msg()” value=“Message”> </BODY> </HTML> Myscript.js: Function msg() { alert("Hello") } 11 JavaScriptIntroduction
  12. 12. Java Script Syntax Issue • JavaScript commands and names are case sensitive. • JavaScript command lines end with a semicolon to separate it from the next command line in the program. • in some situations, the semicolon is optional • semicolons are useful to make your code easier to follow and interpret 12 JavaScriptIntroduction
  13. 13. Displaying some text on web Page • You can write on page by using following statement of Java script- document.write(“message”) document.writeln(“message”) Example: document.write(“<h1><B>My first message</B></h1>” ) ; 13 JavaScriptIntroduction
  14. 14. JavaScript Display Possibilities • JavaScript does NOT have any built-in print or display functions. • JavaScript can "display" data in different ways: • Writing into an alert box, using window.alert(). • Writing into the HTML output using document.write(). • Writing into an HTML element, using innerHTML. • Writing into the browser console, using console.log(). 14 JavaScriptIntroduction
  15. 15. window.alert() <!DOCTYPE html> <html> <body> <h1>My First Web Page</h1> <p>My first paragraph.</p> <script> window.alert(5 + 6); </script> </body></html> 15 JavaScriptIntroduction
  16. 16. 16 JavaScriptIntroduction
  17. 17. document.write() <html> <body> <h1>My First Web Page</h1> <p>My first paragraph.</p> <button type="button" onclick="document.write(5 + 6)"> Try it</button> </body> </html> 17 JavaScriptIntroduction
  18. 18. 18 JavaScriptIntroduction
  19. 19. innerHTML <html> <body> <h1>My First Web Page</h1> <p>My First Paragraph.</p> <p id="demo"></p> <script> document.getElementById("demo") .innerHTML = 5 + 6; </script> </body> </html> 19 JavaScriptIntroduction
  20. 20. 20 JavaScriptIntroduction
  21. 21. console.log() <!DOCTYPE html> <html><body> <h1>My First Web Page</h1> <p>My first paragraph.</p> <p> Activate debugging in your browser (Chrome, IE, Firefox) with F12, and select "Console" in the debugger menu. </p> <script> console.log(5 + 6); </script> </body> </html> 21 JavaScriptIntroduction
  22. 22. 22 JavaScriptIntroduction
  23. 23. Working with Variables & Data • A variable is a named element in a program that stores information. var var_name; • The following restrictions apply to variable names: • the first character must be either a letter or an underscore character ( _ ) • the remaining characters can be letters, numbers, or underscore characters • variable names cannot contain spaces • Variable names are case-sensitive. 23 JavaScriptIntroduction
  24. 24. Types of Variables • JavaScript supports four different types of variables •Numeric variables can be a number, such as 13, 22.5, or -3.14159 •string variables is any group of characters, such as “Hello” or “Happy Holidays!” •Boolean variables are variables that accept one of two values, either true or false •null variables is a variable that has no value at all 24 JavaScriptIntroduction
  25. 25. Declaring/Creating a Variable • Before you can use a variable in your program, you need to declare a variable using the var command or by assigning the variable a value. • Any of the following commands is a legitimate way of creating a variable named “Month”: var Month; Month = “December”; var Month = “December”; 25 JavaScriptIntroduction
  26. 26. Operators in JavaScript • Following operators are used in JavaScript- 1. Arithmetic Operator 2. Comparison Operator 26 JavaScriptIntroduction
  27. 27. Operators in JavaScript • Following operators are used in JavaScript- 1. Arithmetic Operator Operator Meaning Example + Addition 2 + 4 - Subtraction 6 - 2 * Multiplication 5 * 3 / Division 15 / 3 % Modulus 43 % 10 27 JavaScriptIntroduction
  28. 28. Example <body> <script type="text/JavaScript"> <!– var two = 2 var ten = 10 var linebreak = "<br />" document.write("two plus ten = ") var result = two + ten document.write(result) document.write(linebreak) document.write("ten * ten = ") result = ten * ten document.write(result) document.write(linebreak) document.write("ten / two = ") result = ten / two document.write(result) //--> </script> </body> 28 JavaScriptIntroduction
  29. 29. Output two plus ten = 12 ten * ten = 100 ten / two = 5 29 JavaScriptIntroduction
  30. 30. Operators in JavaScript 2. Comparison Operator Operator Meaning Example Result == Equal To x == y false === Equal value and equal type x===y true != Not Equal To x != y true !== not equal value or not equal type x!== false < Less Than x < y true > Greater Than x > y false <= Less Than or Equal To x <= y true >= Greater Than or Equal To x >= y false 30 JavaScriptIntroduction
  31. 31. Built-in JavaScript Functions • Functions provided by the language and you cannot change them to suit your needs. • Some of the built-in functions in JavaScript are shown here: • eval - eval(expr) • eval evaluates the expression or statements • isFinite • Determines if a number is finite • isNaN • Determines whether a value is “Not a Number” • parseInt • Converts string literals to integers, no number  NaN. • parseFloat • Finds a floating-point value at the beginning of a string. 31 JavaScriptIntroduction
  32. 32. JavaScript Functions • A function is a block of organized reusable code (a set of statements) for performing a single or related action. • Begins with keyword “function” and the function name and “( … )” • Inside the parentheses • We can pass parameters to the function • E.g. function myfuc(arg1, arg2) {…} • Built-in and user-defined functions 32 JavaScriptIntroduction
  33. 33. Creating JavaScript Functions Declaration Syntax • Functions are declared using the function reserved word • The return value is not declared, nor are the types of the arguments function function_name(parameters) { JavaScript commands } • parameters are the values sent to the function (note: not all functions require parameters) • { and } are used to mark the beginning and end of the commands in the function. 33 JavaScriptIntroduction
  34. 34. Creating JavaScript Functions: Eg <HTML> <HEAD> <SCRIPT TYPE=TEXT/JAVASCRIPT> <!- - function myMessage() { document.write(“<B>Hello World”); } // - -> </SCRIPT> </HEAD> <BODY> <INPUT TYPE=BUTTON onClick=myMessage() Value=Click > </BODY> </HTML> 34 JavaScriptIntroduction
  35. 35. Event in JavaScript • JavaScript is its ability to help you create dynamic web pages that increase user interaction • The building blocks of an interactive web page is the JavaScript event system. • An event in JavaScript is something that happens with or on the webpage. • A few example of events: • A mouse click • The webpage loading • Mousing over a hot spot on the webpage, also known as hovering • Selecting an input box in an HTML form • A keystroke 35 JavaScriptIntroduction
  36. 36. Event in JavaScript • JS Event Handler • Onclick • onMouseOver • onMouseOut • onLoad • onkeydown 36 JavaScriptIntroduction
  37. 37. JavaScript Object • Object • Number • String • Date • Array • Boolean • Math, etc 37 JavaScriptIntroduction
  38. 38. What is the DOM? • The DOM is a W3C (World Wide Web Consortium) standard. • The DOM defines a standard for accessing documents: "The W3C Document Object Model (DOM) is a platform and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of a document." • The W3C DOM standard is separated into 3 different parts: • Core DOM - standard model for all document types • XML DOM - standard model for XML documents • HTML DOM - standard model for HTML documents JavaScriptIntroduction 38
  39. 39. What is the HTML DOM? • The HTML DOM is a standard object model and programming interface for HTML. • It defines: • The HTML elements as objects • The properties of all HTML elements • The methods to access all HTML elements • The events for all HTML elements • In other words: The HTML DOM is a standard for how to get, change, add, or delete HTML elements. JavaScriptIntroduction 39
  40. 40. • When a web page is loaded, the browser creates a Document Object Model of the page. • The HTML DOM model is constructed as a tree of Objects: JavaScriptIntroduction 40 What is the HTML DOM?
  41. 41. • With the object model, JavaScript gets all the power it needs to create dynamic HTML: • JavaScript can change all the HTML elements in the page • JavaScript can change all the HTML attributes in the page • JavaScript can change all the CSS styles in the page • JavaScript can remove existing HTML elements and attributes • JavaScript can add new HTML elements and attributes • JavaScript can react to all existing HTML events in the page • JavaScript can create new HTML events in the page JavaScriptIntroduction 41
  42. 42. The HTML DOM Document • HTML DOM object model, the document object represents your web page. • The document object is the owner of all other objects in your web page. • If you want to access objects in an HTML page, you always start with accessing the document object. JavaScriptIntroduction 42
  43. 43. Finding HTML Elements JavaScriptIntroduction 43 Method Description document.getElementById() Find an element by element id document.getElementsByTagName() Find elements by tag name document.getElementsByClassName( ) Find elements by class name
  44. 44. Changing HTML Elements JavaScriptIntroduction 44 Method Description element.innerHTML= Change the inner HTML of an element element.attribute= Change the attribute of an HTML element element.setAttribute(attribute, value) Change the attribute of an HTML element element.style.property= Change the style of an HTML element
  45. 45. Adding and Deleting Elements JavaScriptIntroduction 45 Method Description document.createElement() Create an HTML element document.removeChild() Remove an HTML element document.appendChild() Add an HTML element document.replaceChild() Replace an HTML element document.write(text) Write into the HTML output stream
  46. 46. Adding Events Handlers JavaScriptIntroduction 46 Method Description document.getElementById(id). onclick=function() {code} Adding event handler code to an onclick event
  47. 47. Document Object • Java script enable browsers are capable of recognizing individual objects in a HTML page. • Each HTML document loaded into a browser window becomes a Document object. • The Document object provides access to all HTML elements in a page, from within a script. • DOM has following properties- • Anchor • Applet • Body • Cookies • Form • Image • Link • Title • URL , etc 47 JavaScriptIntroduction
  48. 48. Validation in JavaScript 48 JavaScriptIntroduction <!DOCTYPE html><html><body> <h1>JavaScript Can Validate Input</h1> <p>Please input a number between 1 and 10:</p> <input id="numb" type="number"> <button type="button" onclick="myFunction()">Submit</button> <p id="demo"></p> <script> function myFunction() { var x, text; // Get the value of the input field with id="numb" x = document.getElementById("numb").value; // If x is Not a Number or less than one or greater than 10 if (isNaN(x) || x < 1 || x > 10) { text = "Input not valid"; } else { text = "Input OK"; } document.getElementById("demo").innerHTML = text; } </script></body></html>
  49. 49. JavaScriptIntroduction 49

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