A 'Print This Page' Script Using the MS-XMLHTTP object and Regular Expressions, Part 2

In Part 1 we looked at the first two parts of creating our "Printer Friendly" script: creating the dynamic link to PrintPage.asp and adding in the HTML comments indicating which parts of our article should not be shown in the "Printer Friendly" version. In this part, we'll examine the ASP script that does all the work, PrintPage.asp.

The Final Step - Creating PrintPage.asp
Once you have inserted the start and end HTML comment tags in all the appropriate places, all that remains is writing the code for PrintPage.asp, which will display the "Printer Friendly" version of an article. To create this page, simply insert the following code. I won't explain the code here, the comments in the source below should (hopefully) be clear enough. If you have any questions or problems, don't hesitate to email me.

<% option explicit Response.Buffer = True 'declare a variable for the reference page, 'the XMLHTTP Object, and the regular expressions used Dim RefPage, objXMLHTTP, RegEx 'set the RefPage variable to the "ref" querystring 'the JavaScript function above passes the current page URL 'You can use the Request.ServerVariables("HTTP_REFERER") to 'get the page as a last option if needed RefPage = Request.QueryString("ref") if RefPage = "" then response.write "<h3>Invalid reference page</h3>" response.end end if 'set the objXMLHTTP object to the XMLHTTP object from Microsoft Set objXMLHTTP = Server.CreateObject("Microsoft.XMLHTTP") 'perform the HTTP "GET" method via the XMLHTTP object to retrieve 'the called page objXMLHTTP.Open "GET", RefPage, False objXMLHTTP.Send 'give RefPage the text(HTML) from the call above RefPage = objXMLHTTP.responseText 'Create built In Regular Expression object that 'is now included with VBScript version5 Set RegEx = New RegExp RegEx.Global = True 'Set the pattern To look For <!-- START PPOMIT --> tags RegEx.Pattern = "<!-- START PPOMIT -->" 'replace the comment pattern with a rare ASCII character 'i've choosed No 253 in this case, I suppose if you're speaking 'a language other than English this may not be the case but 'the reasoning here is so it will be unique and not interfere 'this the main page content RefPage = RegEx.Replace(refpage,( chr(253) )) 'Set the pattern To look For <!-- END PPOMIT --> tags RegEx.Pattern = "<!-- END PPOMIT -->" 'This time make it replace the comment with another rare 'ASCII character, NOT the one used above RefPage = RegEx.Replace(refpage,( chr(254) )) 'Use this regular expression to "cut out" HTML between the 'start and end comments now the new ASCII characters RegEx.Pattern = chr(253) & "[^" & chr(254) & "]*" & chr(254) 'This will perform the actual striping RefPage = RegEx.Replace(refpage, " " ) 'Don't forget to tidy up :-) Set RegEx = Nothing Set objXMLHTTP = Nothing 'Output your Printer Friendly Page! Response.Write RefPage %>

As you can see it is really quite simple and using the XMLHTTP object instead of something like FSO means that the ASP page is actually executed and not just 'read' as a stream of characters.

A few quick notes before I sign off. Note that if you have version 5.5 or greater of the scripting engines installed on your Web server you can use the non-greedy pattern matching to snip out the omitted areas. (See the article, Picking Out Delimited Text with Regular Expressions for more information on using non-greedy pattern matching!) Specifically, the regular expression pattern would be:

<!-- START PPOMIT -->(.*?)<!-- END PPOMIT -->

To determine what server-side scripting version you're using, check out: Determining the Server-Side Scripting Language and Version. To learn more about the non-greedy pattern in regular expressions check out Picking Out Delimited Text with Regular Expressions.

One important caveat: be careful were you put the HTML comments, ideally make sure that every HTML tag inside the comments is closed off (i.e., <table> with </table>, <td> with </td>, etc.). If you don't you may run the risk of the "Printer Friendly" version not being very friendly at all!

Anyway, Happy Programming!