Question

如何仅使用JS创建下拉列表？示例我有我的HTML，我知道对于HTML的下拉列表，您可以使用select和option标记，但是如果我不更改任何HTML元素，而仅使用Javascript并链接其中的html，则可以使用JS创建Day-Month-Year一年的下拉列表，该怎么做？

我的HTML：

<!doctype html>
<html lang="en">
<head>
  <title> Testing for JS Dropdown</title>
  <style>
    div {
      width: 50%;
      margin: auto;
      height: 200px;
      border: 5px solid black;
      background-color: silver;
    }
    .field {
      padding-left: 10px;
      width: 60px;
      display: inline-block;
    }
    h2 { padding-left: 10px;}
  </style>
  <meta charset="utf-8">
  <script src="prototype.js"></script>
  <script src="JStester.js"></script>
</head>
<body>
  <div>
    <h2> Select Day-Month-Year </h2>
    <p> <span class="field">Day </span><select id="days"> </select></p>
    <p> <span class="field">Month</span><select id="months"> </select></p>
    <p> <span class="field">Year</span><select id="years"></select></p>
  </div>
</body>
</html>

Answer 1

尝试一下。

$(document).ready(function() {
const monthNames = ["January", "February", "March", "April", "May", "June",
  "July", "August", "September", "October", "November", "December"
];
  var qntYears = 4;
  var selectYear = $("#years");
  var selectMonth = $("#months");
  var selectDay = $("#days");
  var currentYear = new Date().getFullYear();
  
  for (var y = 0; y < qntYears; y++){
    let date = new Date(currentYear);
    var yearElem = document.createElement("option");
    yearElem.value = currentYear 
    yearElem.textContent = currentYear;
    selectYear.append(yearElem);
    currentYear--;
  } 

  for (var m = 0; m < 12; m++){
      let monthNum = new Date(2018, m).getMonth()
      let month = monthNames[monthNum];
      var monthElem = document.createElement("option");
      monthElem.value = monthNum; 
      monthElem.textContent = month;
      selectMonth.append(monthElem);
    }

    var d = new Date();
    var month = d.getMonth();
    var year = d.getFullYear();
    var day = d.getDate();

    selectYear.val(year); 
    selectYear.on("change", AdjustDays);  
    selectMonth.val(month);    
    selectMonth.on("change", AdjustDays);

    AdjustDays();
    selectDay.val(day)
    
    function AdjustDays(){
      var year = selectYear.val();
      var month = parseInt(selectMonth.val()) + 1;
      selectDay.empty();
      
      //get the last day, so the number of days in that month
      var days = new Date(year, month, 0).getDate(); 
      
      //lets create the days of that month
      for (var d = 1; d <= days; d++){
        var dayElem = document.createElement("option");
        dayElem.value = d; 
        dayElem.textContent = d;
        selectDay.append(dayElem);
      }
    }    
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<html lang="en">
<head>
  <title> Testing for JS Dropdown</title>
  <style>
    div {
      width: 50%;
      margin: auto;
      height: 200px;
      border: 5px solid black;
      background-color: silver;
    }
    .field {
      padding-left: 10px;
      width: 60px;
      display: inline-block;
    }
    h2 { padding-left: 10px;}
  </style>
  <meta charset="utf-8">
  <script src="prototype.js"></script>
  <script src="JStester.js"></script>
</head>
<body>
  <div>
    <h2> Select Day-Month-Year </h2>
    <p> <span class="field">Day </span><select id="days"> </select></p>
    <p> <span class="field">Month</span><select id="months"> </select></p>
    <p> <span class="field">Year</span><select id="years"></select></p>
  </div>
</body>
</html>

Answer 2

仅使用JAVASCRIPT尝试

UPDATE TransmitterPointsData
SET DynamicDistance = GETDISTANCE(Lat, Longi, Latitude, Longitude)

使用Javascript的下拉列表

2 个答案: