Question

我正在尝试使用纯java脚本制作一个简单的基于Web的时钟应用程序。我认为通用代码是正确的，但我不确定如何在设定的时间间隔内自动调用该函数。我认为window.onload，然后是setInterval方法会这样做。但它不像我预期的那样每半秒自动更新一次。我做错了什么？

<!doctype html>

<html>

    <head>
        <title>Real Time Clock</title>
        <script>

            var time, h, m, s, track;
            track = 0;
            window.onload = function() { setInterval( timeNow(), 100); }

            function timeNow() {

              time = new Date();
              track += 1;
              h = time.getHours();
              m = time.getMinutes();
              s = time.getSeconds();
              if ( s < 10 ) { s = "0" + s; } /* we add a 0 in front of s, when it is lower than 10, because that's what most clocks display, this is for the human user rather than for any need by the computer */
              document.getElementById("time").innerHTML = h + ':' + m + ':' + s;
              document.getElementById("track").innerHTML = track;

            }

        </script>
    </head>

    <body>

        <span id="time">~Waiting for time update.</span><br>
        <span id="track"></span>


    </body>

</html>

Answer 1

似乎工作正常。只需改变

window.onload = function() { setInterval( timeNow(), 100); }

到

 window.onload = function() { setInterval( timeNow, 100); }

＆＃13;

<!doctype html>

<html>

    <head>
        <title>Real Time Clock</title>
        <script>

            var time, h, m, s, track;
            track = 0;
            window.onload = function() { setInterval( timeNow, 100); }

            function timeNow() {

              time = new Date();
              track += 1;
              h = time.getHours();
              m = time.getMinutes();
              s = time.getSeconds();
              if ( s < 10 ) { s = "0" + s; } /* we add a 0 in front of s, when it is lower than 10, because that's what most clocks display, this is for the human user rather than for any need by the computer */
              document.getElementById("time").innerHTML = h + ':' + m + ':' + s;
              document.getElementById("track").innerHTML = track;

            }

        </script>
    </head>

    <body>

        <span id="time">~Waiting for time update.</span><br>
        <span id="track"></span>


    </body>

</html>

＆＃13;

Answer 2

使用setInterval(timeNow,100);代替setInterval(timeNow(),100);

＆＃13;

            var time, h, m, s, track;
            track = 0;
            window.onload = function() { 
              var start = setInterval(timeNow,100);
            }

            function timeNow() {

              var time = new Date();
              track += 1;
              h = time.getHours();
              m = time.getMinutes();
              s = time.getSeconds();
      
              if ( s < 10 ) { s = "0" + s; } 
              document.getElementById("time").innerHTML = h + ':' + m + ':' + s;
              document.getElementById("track").innerHTML = track;

            }

＆＃13;

     

        <span id="time">~Waiting for time update.</span><br>
        <span id="track"></span>

＆＃13;

Answer 3

您正在将undefined（作为调用timeNow的结果）传递给setInterval。您需要传递函数，因此代码将是：

window.onload = function() { setInterval(timeNow, 100); }

如何在Javascript中自动更新时钟？

3 个答案: