JavaScript - Part-1

Java Script
What is JavaScript?
JavaScript was designed to add interactivity to HTML
pages.
JavaScript is a scripting language.
A scripting language is a lightweight programming
language.
JavaScript is usually embedded directly into HTML
pages.
JavaScript is an interpreted language (means that
scripts execute without preliminary compilation).
Everyone can use JavaScript without purchasing a
license.

Java Script
What can a JavaScript do?
JavaScript gives HTML designers a programming tool
- HTML authors are normally not programmers, but
JavaScript is a scripting language with a very simple syntax!
Almost anyone can put small "snippets" of code into their
HTML pages.
JavaScript can put dynamic text into an HTML page - A
JavaScript statement like this:
document.write("<h1>" + name + "</h1>")
can write a variable text into an HTML page.
JavaScript can react to events - A JavaScript can be set to
execute when something happens, like when a page has
finished loading or when a user clicks on an HTML element.
JavaScript can read and write HTML elements - A
JavaScript can read and change the content of an HTML
element.

Java Script
What can a JavaScript do?
JavaScript can be used to validate data - A JavaScript can
be used to validate form data before it is submitted to a
server. This saves the server from extra processing
JavaScript can be used to detect the visitor's browser - A
JavaScript can be used to detect the visitor's browser, and depending on the browser - load another page specifically
designed for that browser
JavaScript can be used to create cookies - A JavaScript
can be used to store and retrieve information on the visitor's
computer

Features Java Script

 Statement Ends with Semicolon
 Handling Old versions of Browers
 Case Sensitive
 Ignores white space (extra space)
• i.e. “computer” and “ computer”

 Insert special characters
• i.e. document.write(“My name is “James””);
•Output:- My name is “James”

 Comments: // Single line comments
/* multi line comments…. */

Java Script
<html>
<body>
<script type="text/javascript">
document.write("This is my first JavaScript!");
</script>
</body>
</html>

Java Script
<html>
<body>
document.write("<h1>Hello World!</h1>");
</script>
</body>
</html>

Java Script
<html>
<body>
<H1>
document.write("Hello World!");
</script>
</H1>
</body>
</html>

Java Script
<html>
<head>
document.write(“Head Section Script!");
</script>
</head>
<body>
document.write(“Body Section Script!");
</script>
</body>
</html>

Java Script
External Java Script
Same script cam be use in several pages
Write the script in a separate JavaScript
file and store the file with xyz.js extension
Use the file in HTML page

Java Script
//External JavaScript file f1.js
document.write(“This is external Script!”);

Java Script
Use the file in another script
<html>
<head>
<script src=“f1.js">
</script>
</head>
<body>
document.write(“Demo of External File!");
</script>
</body>
</html>

Java Script
Variables in Script
RULES:
 Case Sensitive
 Begin with Alphabet Letter or
Underscore
 Character, digit and Underscore only.
i.e.
var age = 25;
var stud_name = “james thomas”;

Java Script
Scope of Variables in Script
 Local
o variable within the function
o lifetime is till the function is in execution

 Global
o variable outside the function
o lifetime is until page closed

Java Script
Datatypes in Script

Empty
 Null
 Boolean
 Char
 Integer
 Long

 Float
 Double
 Date
 String
 Object

Java Script

ParseXXX()
Method
Self Study…

Java Script
Operators:
1) Arithmetic
2) Logical
3) Relational
4) Assignment (shorthand)
5) String
6) Bitwise
7) Conditional (Ternary)
8) Special
9) new

Java Script
Conditional Statements:
1) if
2) if else
3) Nested if
4) Switch case

Java Script
Looping/ Iteration Statements:
1) while
2) Nested while
3) Do… while
4) For
5) Nested for
6) Break
7) Continue

Java Script
<html>
<head>
function message()
{
alert("This alert box was called with the onload
event");
}
</script>
</head>
<body onload="message()">
</body>
</html>

JavaScript - Part-1

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