P3 + M2
Introduction
In this blog I am going explain the fundamentals of scripting
languages, and how they differ from programming languages. I am also going to
talk about the difference between client side and user side programming.
Finally I am going to talk about JavaScript and JQuery.
What is a Scripting Language?
What is a Scripting Language?
A scripting language is a form of programming that is
interpreted. Scripting languages are interpreted one command at a time. The
scripting languages are usually written to enhance the features of a website.
The features are processed on the server but the script on each page runs off
the browser.
Why is it different from a programming language?
Why is it different from a programming language?
Scripting languages are simple languages for simple
tasks. For example, scripting languages have loops and if statements just like
programming languages but for example you can’t do file operations. These are
when you can save to the hard disk and open files, scripting languages cannot
do this because it can be dangerous if a coder was to write JavaScript into a
web page as they could write code to put your personal files on the browser
when you open it. This is why it is better to use scripting languages for
simple tasks such as Logins and forums, whereas with a programming language you
can write operating systems such as Windows 7, Excel and Komodo Edit. This
can’t be done in JavaScript as it is not powerful enough.
What do Scripting Languages interpret?
What do Scripting Languages interpret?
As mentioned earlier scripting languages are
interpreted and example one is PERL, PHP and JavaScript and many others. These
scripting languages are just text files and require an interpreter in order for
the program to be run, just like someone who can’t speak English needs an
interpreter. The web browser such as Internet Explorer or Firefox is the one
which translates the HTML AND CSS into webpages and programs that we
understand.
Client Scripting Languages
Client Scripting Languages
There are two main types of scripting languages
specifically for web purposes; however there are other scripting languages out
there. Client side scripting allows you to interact within a web page. The code
which is needed to process user input is downloaded by the browser.
Example
Example
On the world wide web JavaScript scripts are
client side as they are made by your browser (the client). On the other hand CGI scripts are server side because they run on the Web Server.
<!--[if !supportLineBreakNewLine]-->
<!--[endif]-->
<!--[if !supportLineBreakNewLine]-->
<!--[endif]-->
Server Scripting Languages
With server side scripting languages, completing an
activity requires you to send the code or information to another server
(computer) via the internet. The server runs a program which then processes the
information and returns the result back, which is usually on the web page.
Example
For
example Google, which is a search engine uses server scripting. When a key word
is searched a program on the server searches for a match to that word. If this
was to be done with client side, it would require a browser to download the
whole search engine and index.Example
Difference between client and server
The difference between client and server with the client side scripting the response to interaction is usually immediate once the program has been downloaded. It is usually more secure than server scripting as you are not sending any information over the server. The processing speed of the user’s computer will affect client scripting.
On the other hand with server side scripting, complex processes are more efficient because the program is not downloaded to the browser. A down side to server side is that you need to have measures in place for security reasons when sending sensitive data online because it will be travelling through servers. Finally the server side will be affected by the processing speed of the host server.
JavaScript
JavaScript is a programming language which is used to make web pages interactive. It is run on the computer of the user when they go onto a website; this means that JavaScript doesn’t need to be downloaded onto your computer every time you go on a website. JavaScript is popular with making quizzes and polls. JavaScript and Java are completely different computer languages as Java is a programming language e.g. for coding operating systems and JavaScript is a scripting language.
Common Tasks JavaScript is used for
Over the years JavaScript has changed. At first JavaScript interacting with website was mainly limited to interacting with forms, such as giving the user feedback and deleting certain things they did. JavaScript libraries are very big these days, they take common actions and simplify the process. This makes the process of coding much easier and saves a lot of time. There are other scripting languages for the web but mainly for the client side JavaScript is used. JavaScript is like a programming language but it is not as powerful but it is very complex, if you wanted to do something quickly such as a roll over menu, you would have to do a large amount of coding.
<script>
document.getElementByid(“Good Morning”).innerHTML=’hello’;
</script>
What is JQuery.
The main purpose of JQuery is to allow you to have the same effect as JavaScript but with much less code to write. In other words JQuery is a quicker version of JavaScript because it is in the library within JavaScript. Many companies such as Microsoft and Google use JQuery. JQuery is used widely to code for websites and it uses HTML and CSS. As the code is already written in the JavaScript library it makes life much easier for programmers.
Example
<script>
$(document).ready(function(){
$("p").click(function(){
$(this).hide();
});
});
</script>
Client Side and their purposes (Validation, User interface)
Client Side and their purposes (Validation, User interface)
The main purpose of client side is the validation and
user interface of a web page. For example a form, which has been created, it
may have a validity check such as a presence check in the field. It is very important that web pages
have validation procedures in place so that error from the users is minimised
For example if someone was filling out a form on a website and they missed out
their name field, a validation rule could be a presence check which makes sure
that the user enters something in the box. Another validation check could be
that the website asks the user to enter a certain number e.g. between 1 and
100. This is called a range check and it makes sure that the user doesn't enter
a number that is totally off scale. In terms of the performance of the
computer, it can be compromised because validation is done by user’s computer
and it is done by their browser.
The user interface of any web page is very important. These days we expect something to happen when we click a button or when we go to another page. An example of this is when we hover over a button on Amazon.com the bottom changes colour and flashes. This is a interaction with the user. Another interaction may be, when the user hovers over a picture the picture changes in a slide show. These interactions on a webpage are important as they attract the user to the website and they make the page more interactive and interesting. Google have a classic interaction which is when we search something the results come up as blue and then when we click the link it flashes red, and when you return to your search results the link you previously clicked stays orange.
The user interface of any web page is very important. These days we expect something to happen when we click a button or when we go to another page. An example of this is when we hover over a button on Amazon.com the bottom changes colour and flashes. This is a interaction with the user. Another interaction may be, when the user hovers over a picture the picture changes in a slide show. These interactions on a webpage are important as they attract the user to the website and they make the page more interactive and interesting. Google have a classic interaction which is when we search something the results come up as blue and then when we click the link it flashes red, and when you return to your search results the link you previously clicked stays orange.
The client side environment used to run scripts is usually a
browser. The processing takes place on the end users computer. The code is
transferred from the web server to the user’s computer over the internet and
run directly in the browser. The scripting language needs to be enabled on the
client computer. Sometimes the user may switch the scripting facility off
because of security issues. When this is the case a message usually pops up to
alert the user when script is attempting to run.
Example of Validation (Presence Check) on Client Side:
(While filling in a form you miss out the D.OB. box)
Error Message: Please Enter Blank Field before continuing.
The above is an example of filling in a form and the user forgetting to enter a value for the D.O.B box. This then causes an error message and it doesn't let the user continue until they fill it in. This type of validation is called a 'Presence Check'.
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REFERENCE
JQuery Example - 10/05/2013 - http://bit.ly/7sKk95
JavaScript Example - 10/05/2013 - http://bit.ly/cGI3Jk
Scripting Language - 10/05/2013 - http://bit.ly/fX6SLd
