javascript - 给出了如何通过javascript代码更新时间

Question

var time = new Date();
var hour = time.getHours();
var min = time.getMinutes();
var sec = time.getSeconds();

function myTime() {
  if (hour < 12) {
    sort = "AM";
  } else {
    sort = "PM";
  }
  if (min < 10) {
    min = "0" + min;
  }
  if (sec < 10) {
    sec = "0" + sec;
  }

  document.write("Current time is: " + "<b>" + hour + ":" + min + ":" + sec + " " + sort + "</b>");
}
var myVar = setInterval(function() {
  myTime()
}, 1000);

我编写了这段代码，但运行不正常。如何自动更新秒和分钟？我使用间隔函数来更新时间，但它不更新时间。帮帮我

Answer 1

只需将所有变量放在函数中，这样每当函数调用时，都会获取最新值。

如果您不想每次都重写所有字符串，也可以使用innerHTML。

function myTime(){

    var time=new Date();
    var hour=time.getHours();
    var min=time.getMinutes();
    var sec=time.getSeconds();

    if(hour<12){
        sort="AM";
    }
    else{
        sort="PM";
    }
    if(min<10){
        min="0"+min;
    }
    if(sec<10){
        sec="0"+sec;
    }

//document.write("Current time is: "+"<b>"+hour+":"+min+":"+sec+" "+sort+"</b>");
document.getElementById("demo").innerHTML = "Current time is: "+"<b>"+hour+":"+min+":"+sec+" "+sort+"</b>";
    }
    var myVar=setInterval(function(){myTime()},1000);

<span id="demo"> </span>