Javascript Countdown Timer with user input

Question

我想创建一个倒计时器，用户可以在其中输入日，时，分和秒值的任意组合，并让它倒计时完成。我觉得自己已经掌握了所有的东西，但经过一周的试图解决这个问题，我需要帮助。我将所有的代码随着不同的效果进行混洗。基本上我觉得我错过了一种方式来格式化输入数据的方式，我可以用它来减去当前的日期，但老实说我不知道​​。任何输入都会有帮助。

的Javascript：

function start() { 
    var countdownTimer = setInterval('timer()', 1000); 
} 

function timer() { 
    var d = parseInt(document.getElementById("days").value, 0); 
    var h = parseInt(document.getElementById("hours").value, 0); 
    var m = parseInt(document.getElementById("minutes").value, 0); 
    var s = parseInt(document.getElementById("seconds").value, 0); 

    var now = new Date(); 
    var date = now.getTime(); 

    addDay = now.setDate(now.getDate() + d); 
    addHour = now.setHours(now.getHours() + h); 
    addMinute = now.setMinutes(now.getMinutes() + m); 
    addSecond = now.setSeconds(now.getSeconds() + s); 

    var then = new Date(addHour + addMinute + addSecond); 

    if(d > 0 || h > 0 || m > 0 || s > 0){ 
    var final = then - date; 
    var dd = Math.floor(final/ (1000 * 60 * 60 * 24)); 
    var hh = Math.floor((final/(1000 * 60 * 60)) % 24); 
    var mm = Math.floor((final/1000/60) % 60); 
    var ss = Math.floor((final/1000) % 60); 

    document.getElementById("display").innerHTML = "Time Remaining: " + dd + "D  " + hh + "H " + mm + "M " + ss + "S"; 

    document.getElementById("message").innerHTML = then; 

    if (final < 0) { 
     clearInterval(countdownTimer); 
     document.getElementById("message").innerHTML = "Expired"; 
    } 
    }else{ 
    document.getElementById("display").innerHTML = " "; 
    document.getElementById("message").innerHTML = "Countdown Not Started"; 
    } 
} 

HTML：

<div id="countdowntimer"> 
    <button id="Start" onclick="start();">Start Timer</button> 

    D:<input type="text" id="days" value="0" /> 
    H:<input type="text" id="hours" value="0" /> 
    M:<input type="text" id="minutes" value="0" /> 
    S:<input type="text" id="seconds" value="0" /><br> 

    <div id="display"></div> 

    <div id="message"></div> 
</div> 

Answer 1

如果定时器不是基于日期，但在天，小时，分钟和秒给定的数字，为什么涉及日期？怎么样

function timer(){ 
    var d = parseInt(document.getElementById("days").value, 0); 
    var h = parseInt(document.getElementById("hours").value, 0); 
    var m = parseInt(document.getElementById("minutes").value, 0); 
    var s = parseInt(document.getElementById("seconds").value, 0); 

    var current = ((d * 86400) + (h * 3600) + (m * 60) + s); //the current time left in seconds 
    if (current > 0) { 
     //take one second away, and rerender the seconds split into d, h, m, and s in the html, which you will reuse next time timer() runs 
    } else { 
     //expired 
    } 
}