无法在javascript中回显php值

Question

var countDownDate = new Date("<?php echo file_get_contents('wipetime.txt');?>").getTime();

I'm trying to make a countdown timer. The file "wipetime.txt" changes every few days so I'm trying to make it so I can grab the file when the page loads and countdown to that date.

The problem is that if I echo that php value somewhere on the page, it works. It displays the file contents. However, if I were to echo it inside countDownDate or even an alert, I get nothing. No error, just completely nothing.

I can't see anything wrong at all.

Edit: Heres the entire thing in case you wanna know

<!--Whitelist timer-->
<script>
var countDownDate = new Date("<?php echo file_get_contents('wipetime.txt');?>").getTime();
var x = setInterval(function() {
  var now = new Date().getTime();
  var distance = countDownDate - now;
  var days = Math.floor(distance / (1000 * 60 * 60 * 24));
  var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
  var seconds = Math.floor((distance % (1000 * 60)) / 1000);
  document.getElementById("countdown").innerHTML = "Whitelist expires in " + days + "d " + hours + "h "
  + minutes + "m " + seconds + "s ";
  if (distance < 0) {
    clearInterval(x);
    document.getElementById("countdown").innerHTML = "EXPIRED";
  }
}, 1000);
</script>

Answer 1

There is a possibility that the file wipetime.txt contains some special characters (maybe a carriage return). Two things you can do:

1. Manually check the file for any artifacts and remove them.
2. You should trim the content.

The code:

<?php
$content = file_get_contents('wipetime.txt');
$timeStr = trim($content); // should remove trailing characters like new lines. 
?>

var countDownDate = new Date("<?php echo $timeStr;?>").getTime();