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Force browser not to cache, or force refresh

cjohnson300
cjohnson300 asked
on
2,286 Views
Last Modified: 2013-12-08
I have a html page that uses window.open to open a pdf file in another window.  The problem I am having is that if the pdf has changed, and the browser has opened it recently, the browser returns the cached copy and not the recently changed version.

How can I either force the browser not to ever cache the pdf, or force a refresh on window.open so that the browser goes back to the server to collect the new version of the pdf?

Many thanks in advance
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Commented:
Can you influence the PDF creation or the page displayed by the window.open?

Author

Commented:
the pdf is created on the first page, say page1.asp and once it is created and saved to the server, i then open the pdf using the same page with the window.open.

So in answer to your question, I think that must be both

Commented:
Hi,

before sending any data use

<%
    pStr = "private, no-cache, must-revalidate"
    Response.ExpiresAbsolute = #2000-01-01#
    Response.AddHeader "pragma", "no-cache"
    Response.AddHeader "cache-control", pStr
%>

in the ASP file - must be enough.
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Author

Commented:
no, but i have now and it seems to works great!  I assume that works because the browser thinks each pdf is a different one because of the suffix on the end?  Does your code allow for random numbers from 0 to 100?
function rand ( n ) {
      return ( Math.floor ( Math.random ( ) * n + 1 ) );
}

rand(100); //random number between 1 and 100

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