It is a small computer program written in a scripting language (such as Jave, VB) for a special runtime environment that can interpret and automate the execution of task. Scripting language are usually more limited and somewhat simpler than a full programming languages. It provides code that is relatively easy to read and extend.
Need of Script Language
ü It is used to check client side data validation and error checking in input form.
ü You don't need to spend your whole day as a web server administrator. Just write scripts and let it accomplish the task.
ü It is used to make web pages interactive by creating special effects within a webpages.
ü There is a definite (particular) need to allow users, browsing through a website to actually interact with the webpages.
ü Today's website needs to go much beyond HTML.
Server side scripting
A script that is interpreted by the server is called a server side scripting. It is an instruction set that is processed by the server, and which generates HTML. The resulting HTML is sent as a part of HTTP response to the browser.
Advantages
ü Allow to run programing language that isn't supported by the browser.
ü Enables you to program dynamic web application.
ü Can provide the client (browser) with data that does not reside at the client.
ü Provies improved security measures, since you can write code which can never be viewed from the browser.
Disadvantages
ü Increase the workload of the server.
Client Side Scripting
A script that is interpreted by the browser is called client side script. It processed by browser, not by web server.
Advantages
ü Reduces the web browser workload.
ü Important part of Dynamic HTML.
ü Allow for more interactivity by immediately responding to user's action.
ü Execute quickly because they don't require to the server.
ü Example: Java Script, VB Script etc.
Disadvantages
ü Most recent IE supports VB script, Java script other may not support VB script.
ü The code in your client side script is completely visible to other user.