Script puzzle <script src="ajaxpage.php?emp_id=23" /> ?

Answer 1

Is this correct approach ? its +ves and -ves.

Depends whether you want to use asynchronous (ajax) way or not. Nothing like +ve or -ve. The later method takes more time though.

Which are the correct scenarious to user it?

Ajax way is the correct method there in that sense.

Is this also means that any HTML tag taking "src" tag can be used like this?

src is used to specify the source path. That is what it is meant to do.

Answer 2

I have used this kind of javascript loading for cross domain scripting. Where it is very useful. Here is an example to show what I mean.

[Keep in mind, that JS does not allow cross domain calls from javascript; due to inbuilt security restrictions]

On domain www.xyz.com there lies a service that give me a list of users which can be accessed from http://xyz.com/users/list?age=20 It returns a json, with a wrapping method like following JSON:

{username:"user1", age:21} 

If I request this json wrapped in a method like as follows:

callMyMethod({username:"user1", age:21})

Then this is a wrapped json which if loads on my page; will try to invoke a method called callMyMethod. This would be allowed in a <script src="source"> kind of declaration but would not be allowed otherwise.

So what I can do is as follows

<script language="javascript" src="http://xyz.com/users/list?age=20"&gt;&lt;/script&gt;
<script language="javascript">
    function callMyMethod(data)
    {
      //so something with the passed json as data variable.
    }
</script>

This would allow me to stuff with JSON coming from other domain, which I wouldn't have been able to do otherwise. So; you see how I could achieve a cross domain scripting which would have been a tough nut to crack otherwise.

This is just one of the uses.

Other reasons why someone would do that is:

• To version their JS files with releases.
• To uncache the js files so that they are loaded on client as soon as some changes happen to js and params being passed to URL will try to fetch the latest JS. This would enable new changes getting reflected on client immediatly.
• When you want to generate conditional JS.

The usage you have specified in example wouldn't probably serve much purpose; would probably just delay the loading of page if processing by server takes time and instead a async ajax call would be much preferred.