Html javascript

Basics of HTML (Hyper Text
Markup Language)
 HTML is used to render Web pages
Rendering may differ from a browser to another
It has no computation power and should include
some Scripting language, like Java Script or
VBScript to produce User interactive Rendering
Pages
Despite several design tools, we should learn
some basics of HTML to be good web
developer.
Monday, October 13, 2014sohamsengupta@yahoo.com 1

Some basic tags of HTML
The MIME type is text/html (details on MIME
later on)
Apart from <html>, <head>, <title>, <body>, and
6 heading tags like <h1>…<h6>, we have tags
like <form>, <b>, <u>, <i>, <a>, <ul>, <ol>,
<table>, <input>, <select> et al, to mention a
few.
Not all these tags require closing, but it’s a good
practice to close all tags when over.
Most of the tags have attributes, and it’s a
common malpractice to avoid double/single
quotes enclosing the attribute values.

Hey Man! Quotes Must!
 For Example, <input type=“text”
name=“fname” value=“Aditya Narayan”> is
Okay.
But, not the following one… <input
type=text name=fname value=Aditya
Narayan>
In the second case, for some browsers
shall truncate the part Narayan from the
field.

Form Tag and its Importance
 The main power of Web is how easily and fast it
interacts with the server and processes the user
inputs, and what transfers data from the client to
the server is the <FORM> tag.
It defines mainly 2 attributes, though not
mandatory but expected, are action and
method. By default method is GET (details later)
The action contains the URL that the FORM is
submitted to and transfers the user-input data to.
Form may contain some <input> field as shown
in next slide, some <select> field, and a Submit
Button or a Button leading to the Submit event.

Inside a <FORM> tag <html><head><title>Welcome to JISCE</title></head><body>
<form action=http://myhost:myport/myURI><pre>
Enter name: <input type=“text” name=“myName”>
Enter ID: <input type=“text” name=“myId”>
<select name=“mySkill”>
<option value=“Java SE”>Java SE 1.4</option>
<option value=“Java EE”>Java EE 1.4</option>
<option value=“Java ME”>Java 2 ME </option></select>
Gender <input type=“radio” name=“mySex” value=“Male”>Male
<input type=“radio” name=“mySex” value=“Female”>Female
Check if already registerd <input type=“checkbox”
name=“regStatus” value=“regd”>
<input type=“Submit” value=“Done”></pre>
</form>
</body>
</html>
View At the Code above rendered in IE 6

Inside the <INPUT> tag
<INPUT> tags don’t need to be closed.
With this, we can take any text data, password,
checkbox, radio button, Submit Button, Hidden
Form Field, Any Button, A File to Upload etc.
The mandatory “type” attribute determines what
the INPUT is going to render.
 Example, <input type=“text” name=“fname”>
The name attribute is must, too. It lets the server
fetch the data “fname” from the data entered
here
More on these follows…

More on <INPUT> tag
<input type=“password” name=“pwd”>
<input type=“radio” name=“sex” value=“Male”>
Male
<input type=“radio” name=“sex”
value=“Female”>Female
The above 2 radios must have same name
else both can be selected at time that’s not desired
The value attribute must be present with radios
and You have to render, too; else the user shall
not see what’s for what option. The 2 need not
be same.

<INPUT> tag…contd.
 <input type=“checkbox” name=“skill” value=“Java
SE”>Java SE
<input type=“checkbox” name=“skill” value=“Java
EE”>J2EE
<input type=“checkbox” name=“skill” value=“Java
ME”>J2ME
 Check boxes with same name can be multi-checked at
a single time. They must have values and the rendered
text should be there to tell the user what’s what option
and the value attribute may not be same as the text
rendered. The server shall accept the value attribute’s
values.
 Here, the server shall consider the “Java EE” but not the
rendered text J2EE.

<INPUT> tag… contd.
<input type=“hidden” name=“hdn1”
value=“logged”> This shall not be
rendered in the browser but are often
required for Session tracking (details later)
<input type=“submit” value=“Done”>
<input type=“button” name=“btn1”
value=“Click”>
<input type=“file” name=“upldFile”> shall
open a File type input on browsing.

<select> Tag as Drop-down list
<select name=“skill”>
<option value=“Java”>Java</option>
<option value=“CPP”>C++</option>
<option value=“C#”>C-Sharp</option>
</select>
It should have a name, so to let the server
retrieve the data skill from the form, after it’s
submitted.
Also, Server shall get the value “CPP”, not “C-Sharp”

Java Script for Client Side
Validation
Sometimes, you can’t rest assured with the data
that the user inputs through the client browsers
as they have to pass several validation and
conform to certain constraints. Like, the user
may be required to fill up all the fields in the form
and then submit. Also, the user may input some
Alphabets where only numeric data is required.
All these things must be taken care of by the
server side program.
But, better if we could check them at the client
side, thus saving the time of a round-trip to the
server. Scripting languages like JavaScript used.

A Simple Form validation with Java
Script
<script language=“JavaScript”>
function chkForm(){
var msg=“”;
if(document.forms[0].myName.value==“”){
msg+=“Name can’t be blank!n”;
}
if(document.forms[0].myCity.value==“”){
msg+=“City can’t be blank!”;
}
if(msg==“”) return true;
else{
alert(msg);
return false;
}
}
</script>

The HTML Code
<body>
<form action=“myURL” onsubmit=“return chkForm()”>
Enter Name: <input type=“text” name=“myName”>
<br>Enter City: <input type=“text” name=“myCity”>
<input type=“submit” value=“Submit”>
</form>
</body>
</html>
FormValidation.html
 onsubmit=“return chkForm()” Note the return
keyword, without which it’d not work!

Brief history of JavaScript
Netscape developed a scripting language called LiveScript
Supported both client side and server side scripting
Netscape Navigator 2
(support for java applets and LiveScript
renamed as JavaScript1.1)
Microsoft- JScript IE 3
1997 ECMA (European
Computer Manufacturers
Association)
Standardized ECMA script
Opera
supporting
JavaScript 1.1
W3C standardized DOM to access HTML and XML
JavaScript 1.2

Programs
executes on the
server and sends
the response
Response
HTML file
JAVA
SCRIPT
Request
Client Web Server
Script
executes
locally and
interacts with
the browser
Servlet files
JSP files
HTML files

Uses
• To create more interactive pages- client side validations etc.
• To generate html dynamically.
• Event handling
• To enhance browser capabilities by giving it a better look –
printing on status bar etc.
• Interaction with embedded components like applets and active
x controls.
Language Features
• Object based language:no object inheritance and subclassing. Object -based
because it depends on built-in objects to function.
• Semicolon, as separator for multiple statements in the same line.
• Syntax similar to c++ and java
• Case sensitive
• Loosely typed
• Platform independent
• Interpreted

External Script
<HTML>
<HEAD>
<BODY>
<SCRIPT LANGUAGE=“JavaScript”
SRC=“JSfile.js”>
</SCRIPT>
</BODY>
</HTML>
JSfile.js
document.write(“Hello”)
Scripts inside body and head
Inside head only declarations should be done. No write
statements must appear inside head tag.
<HTML><HEAD><TITLE>Hello</TITLE>
<SCRIPT>
document.write(“Hello java script”)
</SCRIPT>
</HEAD>
<BODY></BODY>
</HTML>
Incorrect

Java Script Data Type and Scope
 Java Script is loosely typed and it
supports Data Types like String, Date,
Array etc. and totally objects.
 A variable defined with keyword var
inside a function is a local variable.
Otherwise it has scope global to the entire
HTML page.
 We, however, must not indulge in the
luxury of dealing with Language basics.

A Simple variable and function
example
<html><head></head>
<script>
age=90;
function fun(){
age=26;
alert("Age = "+age);
}
</script>
<input type="button" value="Show Age" onclick="fun()">
<input type="button" value="Show Age12" onclick="sd()">
<script>
function sd(){
}
</script>
<body>
</body></html> See this execute

Continuation to The Code
 Here age has global scope. Now if we modify
the code as including
function fun(){
var age=26;
} we shall get different output.
 If we omit the statement age=90; we get different
situation. But if we associate a var with age, it’d be same.
 After this example we not only got to learn about the scope of
variables, but we proved that declaring a variable with var
keyword doesn’t always localize it.

Event handling with Java Script
 There’s nothing like consulting the
documentation of Java Script. We shall learn to
use Java Script with HTML with hands-on
practice.
Sometimes we shall need to embed Java Script
in HTML and position elements dynamically.
Some event-handlers: onclick, onkeyup,
onkeypress, onkeydown, ondblclick, onchange,
Following shall be some assignments we’d
discuss.

Assignments on Java Script Event
Handling-1
There’ll be a form having 2 text fields and
a checkbox. The 2nd text needs only
numbers. So, Typing sans numeric shall
not be allowed. Now, the checkbox if
checked, on clicking the submit button, the
browser will ask for confirmation whether
to submit or not. If both the fields are not
filled up, the form shall never be
submitted.

Handling-2,3
 There should be a Hyper link that links to a
page. As you make the mouse cursor go over
the link, it’d change font color and size. As you
mouse-out, it should be restored.
 There should be a form that takes 2 text fields,
name and Phone No. The Phone No. must be
numeric. Also, there should be a checkbox
asking for if there is an alternative phone
Number to be provided, which, when checked,
will display another text field taking only
numbers and un-checking will make it disappear.

Handling-4,5
 There should be a text area, and you can type
up to 100 characters. As you keep on typing, a
text indicating how many characters more
remain, shall be displayed continuously.
There should be 2 text fields taking two
numbers. A button should be there disabled until
both the text fields are filled up. However, if you
delete any of the numbers, the button should
become disabled again. Otherwise, clicking the
button, the sum should be displayed.

Frames and Java Script:
Assignment
 There should be 2 frames on a page. The LHS
frame should contain link to a page say 2.html,
in various ways, to open in the same and parent
frames, in a new window, and in the same
window. The page 2.html, would have buttons to
close the window in various ways.
 You would need some knowledge on DHTML
and Cascading Style Sheets (css) to solve some
of the assignments. So, the next few slides
follow…

Three ways to include style
• Embedded style
• Inline style
• Linked styles
Setting up style info- an example
Microsoft way
BODY { font: 12 pt Arial; color: navy; margin-left:
0.25in }
H1 { font: 18 pt Arial; color: red }

Embedded style : <Style> tag
<html><head>
<style type="text/css">
BODY { font: 12 pt Arial; color: navy; margin-left: 0.25in}
H1 { font: 18 pt Arial; color: red}
</style>
</head>
<body>
<h1>Dynamic Web Pages</h1>
The need of dynamic web pages; an overview of DHTML,
cascading style sheet, comparative studies of different
technologies of
dynamic page creation
</body></html>

Inline style
<table style="font: 12 pt Arial; color: green; font-weight:
bold">
<tr><td>Name</td><td>Reg No. </td></tr>
<tr><td>XXXX</td><td>55555</td></tr>
</table>

Linked style
• Linking to a style info in a separate file.
BODY { font: 12 pt Arial; color: navy; margin-left:
0.25in}
H1 { font: 18 pt Arial; color: red}
style.cs
s
<html><head>
<link rel=“stylesheet” href=“style.css”>
</head>
<body><h1>Dynamic Web Pages</h1>
The need of dynamic web pages; an overview of
DHTML,cascading style sheet, comparative studies of
different technologies of dynamic page creation
</body></html>

Html javascript

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