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Force browser not to cache, or force refresh

cjohnson300 asked
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
Watch Question

Can you influence the PDF creation or the page displayed by the window.open?


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


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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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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