javascript tabriz university 2009. its september 1995
Post on 12-Jan-2016
219 Views
Preview:
TRANSCRIPT
JavaScript
Tabriz university2009
Its September
1995
NetscapeVersion 2.0 of
browser is released.
Its first version to come with
the scripting language.
the name of the language was first
Mocha and then, when released,
LiveScript
In December of that year
Netscape made a marketing deal with
Sunand renamed the language to
JavaScript
What is JavaScript?
JavaScript is a client-side scripting language. If the browser supports the
language, JavaScript grants access to the current page and lets the
script determine properties of the client, redirect the user to
another page, access cookies, and do much more.
Microsoft included JavaScript support from Internet Explorer version 3 onward (mid-1996).
For legal reasons the language was called
JScript.
Microsoft started to include additional,
IE-only features to JScript.
In 1997, the standard
ECMAScript (ECMA-262) was published;
JavaScript is therefore the first implementation of that standard.
ECMAScript became an ISO norm in 1998.
ECMA: European Computer Manufacturers Association
Around 1997 or 1998, the browser war between Netscape and Microsoft reached a climax,
with both vendors adding new, incompatible functionality
to version 5 of their browsers.
Vs
Netscape scrapped the idea of releasing browser version 5 and decided to start all over with
Netscape 6,
which helped Internet Explorer to
expand its market share to over
90%.
It took the then-founded
Mozilla project several years to come to life again.
The very popular
Firefox browser was based on Mozilla and started to take market
share away from Microsoft.
Other browsers, by the way, support JavaScript as
well. Differences are subtle, but still can be extremely annoying when one is developing a
browser-agnostic web application.
Internet Explorer
Mozilla
• Firefox• Epiphany• Camino• Galeon
Opera
Konqueror
Safari
Java Vs JavaScript
Java
• 1991• Sun Microsystems.• Called Oak.
• 1995• Called Java.
Java
A simple, secure, portable, object oriented, robust, multi-threaded, architecture-neutral, interpreted, high performance, distributed and dynamic programming language.
Java Vs JavaScript
• JavaScript was developed by Netscape• Java was developed by Sun
Java Vs JavaScript
• JavaScript–Cannot draw, multi-thread, network or do I/O
• Java–Cannot interact with Browser or control content
Java Vs JavaScript
• JavaScript–Cannot draw, multi-thread, network or do I/O
• Java–Cannot interact with Browser or control content
JavaScript
• We’ll call collections of JavaScript code
scripts, not programs• JavaScript and Java are only related through
syntax• JavaScript’s support for objects is very
different
Object Orientation and JavaScript
• JavaScript is NOT an object oriented programming language:– Does not support class based inheritance– Cannot support polymorphism
Object Orientation and JavaScript
• JavaScript objects are collections of properties, which are like the members of classes in Java and C++
What is it used for today?
• Handling User Interaction:– Checking for accuracy and appropriateness of
data entry from forms– Doing small calculations/manipulations of forms
input data– Save data as cookie so it is there upon visiting the
page• Reduce web server processing load • Reduce delay when users’ input is wrong
• Generating Dynamic HTML documents• Controlling applets and calling Java from
JavaScript• Accessing JavaScript from Java• Allow further capabilities together with other
technologies:– DHTML ( Dynamic HTML)– AJAX (Asynchronous JavaScript and XML)
Language Basics
JavaScript in HTML
• directly, as in<script type = “text/javaScript">
JavaScript script –</script>
• Or indirectly, as a file specified in the src attribute of <script>, as in
<script type = "text/javaScript"src = "myScript.js">
</script>
Example
<HTML> <BODY> <SCRIPT TYPE=“text/javascript”> <!--
// this is a comment
document.write(“Hello World!!”); alert(“Done!”) // --> </SCRIPT> </BODY></HTML>
Syntax
• Variables• Functions• Objects• …
• Syntax based on C/C++/Java• Case Sensitive
I need JS code
WRITE
STEAL
References:
• JavaScript™ Phrasebook: Essential Code and Commands– By Christian Wenz– Sams
top related