如何使用javascript计算小时数，分钟数，秒数

Question

我创建了一个在线考试系统，并且在在线考试系统中添加了一个倒数计时器。以下是我的JavaScript代码。 PLZ检查

<h2><p style="float: right" id="countdown"></p></h2> 

<script> 
    $(document).ready(function() { 
$examination_test_id = $("#examination_test_id").val(); 
     $time_limit = $("#time_limit").val(); 
     var d = new Date($time_limit); //14-August-2016 01:20:00 
     var hours = d.getHours();  //01 
     var minute = d.getMinutes(); //20 
     var minutes = hours * 60 + minute; 
     var seconds = 60 * minutes;  //00 
     console.log(seconds); 
     if (typeof (Storage) !== "undefined") {  //checks if localStorage is enabled 
      if (sessionStorage.seconds) {      //checks if seconds are saved to localstorage 
       seconds = sessionStorage.seconds; 

      } 
     } 
     function secondPassed() { 
      var minutes = parseInt((seconds)/60); 
      var hours = parseInt(minutes/60); 
      var remainingSeconds = seconds % 60; 
      if (remainingSeconds < 10) { 
       remainingSeconds = "0" + remainingSeconds; 
      } 

      if (typeof (Storage) !== "undefined") { 
       sessionStorage.setItem("seconds", seconds); 
      } 

      document.getElementById('countdown').innerHTML = hours + ":" + minutes + ":" + remainingSeconds; 

      if (seconds == 0) { 
       clearInterval(myVar); 
       document.getElementById('countdown').innerHTML = alert('Timeout'); 
       window.location.href = base_url + "student/Examinations/check_answer/" + $examination_test_id; 

       if (typeof (Storage) !== "undefined") { 
        sessionStorage.removeItem("seconds"); 
       } 
      } else { 
       seconds--; 
      } 
     } 
     var myVar = setInterval(secondPassed, 1000); 

    }); 
}); 
</script> 

我的问题：coundown计时器应在1时20分零零秒开始，但对我来说，倒数计时器在01:80:00开始，为什么呢？请检查我的javascript代码

Answer 1

var minutes = hours * 60 + minute;

1小时20分钟总共80分钟。你应该改变该行只是有var minutes = minute;

Answer 2

在几分钟内，你的总走，

var minutes = hours * 60 + minute; 
    80= 1*60 + 20 

Answer 3

在不到5秒钟，我只是找到了答案：Javascript return number of days,hours,minutes,seconds between two dates

或JavaScript seconds to time string with format hh:mm:ss

所以请在发布这类问题之前稍微搜索一下