This is partially PERL and partially javascript (Sorry)

Basically, I want to send an HTTPRequest to the server. If the file =DOES NOT= exist, it throws back an error as a TEXT response. If it DOES exist, it passes back the file as a BLOB. (Not really sure how to send a file as a BLOB from PERL - which is the point of this question)

** Using "Content-type: attachment; application/zip" and "content-disposition" to invoke the save dialouge I can just about understand ... but that will not report an error if the file doesn't exist. (The file is accessed by user entering a code number into a form, so a wrong number needs to throw an error warning)

Here is the basic code:

CLIENT SIDE:
function downFile(){
var formData = new FormData();
formData.set('email','$email');
formData.set('gf_line','$line');
formData.set('code','$code');
var xhttp = new XMLHttpRequest();
    xhttp.onreadystatechange = function() {
    if (this.readyState == 4){
        if (this.status == 200) {
            if (xhttp.responseType == 'text' || xhttp.responseType == 
+'') {
            alert('Sorry, but there appears to be an error\\nThis coul
+d be:\\n\\n- The email address entered\\ndoes not match the email in 
+database\\n\\n- The code you entered is incorrect\\n\\nPlease check y
+our details, and try again');
                    window.history.back();
                    return false;
                    }
                    else if (xhttp.responseType == 'blob'){
            // Create a new Blob object using the response data of the
+ onload object
            var blob = new Blob([this.response], {type: 'application/z
+ip'});
            //Create a link element, hide it, direct it towards the bl
+ob, and then 'click' it programatically
            let a = document.createElement("a");
            a.style = "display: none";
            document.body.appendChild(a);
            //Create a DOMString representing the blob and point the l
+ink element towards it
            let url = window.URL.createObjectURL(blob);
            a.href = url;
            a.download = 'Branded Files.zip';
            //programatically click the link to trigger the download
            a.click();
            //release the reference to the file by revoking the Object
+ URL
            window.URL.revokeObjectURL(url);
            }
        }
        }

    xhttp.open("POST", "download.pl", true);
    xhttp.send(formData);
}
</script>

SERVER SIDE:
...
..
.
if ($inEmail ne $email){
print "content-type: text/html\n\n";
print "500";        # Returned as a "TEXT" response
exit;
}
else{
open FILE, "<", "../data/$user/$dir/$code/$fileCode.zip";
binmode FILE;
while(<FILE>){
$file.=$_;
}
close FILE;
#print "content-type: text/html\n\n";
#print "content-type: application/zip\n";
#print "content-disposition: attachment; filename='Branded Files'\n\n"
+;
print $file;        # Returned as a "BLOB" response
[download]

Both responses return as text

The theory is that the code in the else statement will create a fake anchor, load the blob into it, emulate a click and thus invoke the "SAVE" dialogue. Admit this is "copy / paste" so - whilst I understand what it's doing - it's not my code

In a nutshell, I want an alert if the file does not exist, or a SAVE dialogue if it DOES exist, ideally without navigating away from the page. There may be an easier way to do it, so open to suggestions

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.