Strange behavior of length function in IE

FaneDuru · Feb 10, 2010

I have a text box keeping the IP of the visitor.
I obtain IP in a text box ('ipaddr') of a form named 'myform' using the next script:

Code:

var ip = '<!--#echo var="REMOTE_ADDR"-->'

function ipval() {
document.myform.ipaddr.value='Your IP: '+ip;
}

I would like to detect if the file is opened from local computer or from my domain trying to measure the length of the text in this text box. I must adapt the code because the company hosting the domain is adding a banner at top of tha page and I need to position some tags according to that... It works in FireFox but not in IE:

Code:

 var sT =document.myform.ipaddr.value;
 if (sT.length = 41){
    alert('local')
    //do something...
    }else {
    alert('hosted')
    //do something else...
 }

Length of the string is always 0 in IE...
Can you help on that issue ?
Thanks in advance!
Fane Duru

jpadie · Feb 10, 2010

Code:

if (sT.length = 41){

isn't a single = sign an assignment operator in javascript? i thought it was like php and used == as a comparison operator.

FaneDuru · Feb 10, 2010

I used:

Code:

if (sT.length == 41){

I have just wrongly written in the posted code...
I am afraid that the problem is connected with the way of reading scripts for the two browsers. I have used some alerts and in the moment of alert in the text box of IE it is really nothing. In Firefox is already the IP...

FaneDuru · Feb 10, 2010

Is it another simple way to identify if the file is on the local computer or is hosted ?

Thanks,
Fane Duru'

jpadie · Feb 10, 2010

caveat: i'm no javascript expert...

are you definitely parsing (on your local and remote machines) your html for SSI?

to determine the remote ip address, have you tried using a java method instead? or aswell?

and why are you referencing a form control rather than the ip variable itself?

Code:

var ip = '<!--#echo var="REMOTE_ADDR"-->';
document.onload = function(){
  if (ip.length > 15) { //not an IP address
   if (java && java.net){
    ip = ''+java.net.InetAddress.getLocalHost().getHostAddress();
   } else {
    ip = 'unknown';
  }
 }
}

as to whether the file is remote or local, how about just testing the location.href to see whether it matches your remote domain?

Code:

var myDomain = '[URL unfurl="true"]http://www.domain.com';[/URL] //hard code
function isRemote(){
  var l = (location.href).toLowerCase();
  if (l.indexOf(myDomain) === -1) return false;
  return true;
}

feherke · Feb 11, 2010

Hi

jpadie said:
caveat: i'm no javascript expert...

Code:

[red]document[/red].onload = function(){

That explains it. Should be [tt]window.onload[/tt]. ;-)

Anyway, if you want to know if the request came from the local network or from outside, then why not pass that information to JavaScript instead of the remote address ?

Code:

var islocal=<!--#if expr="$REMOTE_ADDR = /^(192|127)\..*/" -->true<!--#else -->false<!--#endif -->

Tested with Apache.

Feherke.

http://free.rootshell.be/~feherke/

FaneDuru · Feb 11, 2010

Thanks jpadie,
I am not a javascript expert, too. I think it is obvious... You are right in both cases. I was looking for something like your isRemote() function. It happened I had such a form keeping visitor IP on my page and I thought 'I am clever' using it to determine the host...
Now I could build the function based on my previous thought and your idea to use the variable:

Code:

ip = '<!--#echo var="REMOTE_ADDR"-->';// it has been declared prior to that...
function isRemote(){
  if (ip.length > 15) { //not an IP address
     return false;
  } else {
     return true;
  }
}

Your code:

Code:

 ip = ''+java.net.InetAddress.getLocalHost().getHostAddress();

returns local IP 127.0.0.1 in both cases using Firefox and returns nothing in IE and Google Chrome.
Anyhow your second suggestion is the one I will use.

Thanks again,
Fane Duru'

FaneDuru · Feb 11, 2010

Hi feherke,

I am afraid I am not able to understand your suggestion... Is that javascript...? I have tested it with IE, Firefox and Chrome and all of them returns 'undetermined' for the variable...
Is it something which I miss?

I did not use document.onload because at <body onload...> I am calling another function.

Fane Duru'

jpadie · Feb 11, 2010

feherke's suggestion is a conditional server side include.

@feherke
as you have already pointed out elsewhere, i'm not myself today!

feherke · Feb 11, 2010

Hi

Fane Duru' said:
Is that javascript...?

It is similar to you initial code :

Code:

var ip = '<!--#echo var="REMOTE_ADDR"-->'

Code:

var ip = '127.0.0.1'

My code sets the islocal JavaScript variable to [tt]true[/tt] for local requests ( remote IP address starting with 192 or 127 in my example ) :

Code:

var islocal=<!--#if expr="$REMOTE_ADDR = /^(192|127)\..*/" -->true<!--#else -->false<!--#endif -->

Code:

var islocal=true

As I mentioned, the suggested SSI was tested with Apache. In case you use other web server, the interpretation of SSI directives may vary.

Feherke.

http://free.rootshell.be/~feherke/

BillyRayPreachersSon · Feb 11, 2010

Is it (sic) another simple way to identify if the file is on the local computer or is hosted ?

If locally you are using the "file" protocol, then yes:

Code:

alert(location.protocol);

If you are running from a web server locally, then this will obviously not work.

Dan

Coedit Limited - Delivering standards compliant, accessible web solutions

Dan's Page [blue]@[/blue] Code Couch:

http://www.codecouch.com/dan/

Code Couch Tech Snippets & Info:

http://www.codecouch.com/

FaneDuru · Feb 11, 2010

Thanks Dan,

I have also used:

Code:

if(location.protocol == 'file:'){alert('local');}else if(location.protocol== 'http:'){alert('remote');}

and worked very well as you suggested.

Fane Duru'

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Strange behavior of length function in IE

FaneDuru

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jpadie

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FaneDuru

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FaneDuru

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jpadie

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feherke

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FaneDuru

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FaneDuru

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jpadie

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feherke

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BillyRayPreachersSon

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FaneDuru

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