我在下拉列表中尝试了下一个和前 5 年的 html 代码。我正确地获得了下一个 5 年。我如何获得前 5 年

Question

请他把密码发给我

function populatedropdown(yearfield){
var today=new Date()
var yearfield=document.getElementById(yearfield)
var thisyear=today.getFullYear()
for (var y=0; y<5; y++){
yearfield.options[y]=new Option(thisyear, thisyear)
thisyear+=1
}
yearfield.options[0]=new Option(today.getFullYear(), today.getFullYear(), true, true) //select today's year
}

</script>
  </head>
  <body>
<form action="" name="someform">
<select id="yeardropdown">
</select> 
</form>

<script type="text/javascript">

//populatedropdown(id_of_day_select, id_of_month_select, id_of_year_select)
window.onload=function(){
populatedropdown("yeardropdown")
}
</script>
  </body>
</html>

Answer 1

尝试更改 for 循环应该执行 -5 到 5

for (var y=0; y<5 && y>(-5); y++){
yearfield.options[y]=new Option(thisyear, thisyear)
thisyear+=1
}

Answer 2

试试这个

function populatedropdown(yearfield) {
  var today = new Date(),
      yearfield = document.getElementById(yearfield),
      beforeYears = 3
      afterYears = 5,
      thisyear = today.getFullYear();
  
  for (var year = thisyear-beforeYears, index = 0; 
           index <= beforeYears + afterYears; 
           index++, year++) {
    yearfield.options[index] = new Option(year, year);
  }
  yearfield.value = thisyear;
    //select today's year
}

//populatedropdown(id_of_day_select, id_of_month_select, id_of_year_select)
window.onload = function() {
  populatedropdown("yeardropdown")
}

<form action="" name="someform">
  <select id="yeardropdown">
  </select>
</form>

我在下拉列表中尝试了下一个和前 5 年的 html 代码。我正确地获得了下一个 5 年。我如何获得前 5 年

i tried a html code for next and previous 5 years in a drop down.. i got next 5 years properly.. how can i get previous 5 years

html

javascript

drop-down-menu