Using PHP variables in a Javascript function

I am trying to add a PHP variable $i, into a form element using a Javascript function, however this doesnt seem to be working at all, does anyone have any ideas why this may be? I am a novice coder so it may be something obvious. Any help please?

My code is:

HTML:

        <script type="text/javascript"> 
        function addvote() {
        var f = document.getElementById('vote');
        var entry_num = document.getElementById('entry_num')
        alert("document.write(entry_num)";
        document.forms.vote.entry_num.value=("<?php echo $i; ?>");
            if (f.entry_num.value!="")    {
            alert ("submitting vote");
                f.submit();
                                        }
                    else{
                        alert("error")
                        }
                           }
        </script>

Thanks

 

Instead do like this:

PHP:

<?php
print "<script type=\"text/javascript\">\n";
print "function addvote() {\n";
print "var f = document.getElementById('vote');\n";
print "var entry_num = document.getElementById('entry_num')\n";
print "alert(\"document.write(entry_num)\";\n";
print "document.forms.vote.entry_num.value=(" . $i . ");\n";
print "if (f.entry_num.value!=\"\") {\n";
print "alert (\"submitting vote\");\n";
print "f.submit();\n";
print "}\n";
print "else{\n";
print "alert(\"error\")\n";
print "}\n";
print "}\n";
print "</script>\n";
?>


This must work now.