Question

我找到了有关如何创建用于选择年份的动态下拉列表的代码，但是我不知道如何为下拉列表添加默认值，这是我在上面找到的代码

HTML looping option values in drop down list

HTML

<select id="year"></select>

JS

var start = 2018;
var end = new Date().getFullYear();
var options = "";
for(var year = start ; year <=end; year++){
  options += "<option>"+ year +"</option>";
}
document.getElementById("year").innerHTML = options;

我这样尝试过，但是不起作用

<select id="year">
<option value=''>Year</option>    
</select>

还有这个

var start = 2018;
var end = new Date().getFullYear();
var options = "<option value=''>Year</option>";
for(var year = start ; year <=end; year++){
  options += "<option>"+ year +"</option>";
}
document.getElementById("year").innerHTML = options;

我想要的结果是这样

<select id="year">
<option value=''>Year</option> 
<option value=''>2018</option> 
<option value=''>2017</option>   
</select>

有人知道怎么做吗？

不会扩展会有很多答案，谢谢大家，我将尝试您的答案

Answer 1

只需将selected属性添加到option之一中，使其成为默认的选定选项。

<select>
<option>1</option>
<option selected>2</option>
<option>3</option>
</select>

<select id="year">

</select>
<script>
var start = 2010;
var end = new Date().getFullYear();
var options = "<option value='' selected>Year</option>";
for(var year = start ; year <=end; year++){
  options += "<option>"+ year +"</option>";
}
document.getElementById("year").innerHTML = options;
</script>

Answer 2

尝试一下：

var start = 2015;
var end = new Date().getFullYear();

var arrDate = function(start, end) {
    var count = (end - start) + 1;
    return Array.apply(0, Array(count)).map(function (element, index) { 
        return index + start;  
    });
}

arrDate(start, end).forEach(function(v) {
    document.getElementById("year").innerHTML += "<option value='"+v+"'>"+ v +"</option>";
});

<select id="year">
<option value=''>Year</option>    
</select>

Answer 3

好吧，快到了，尝试下面的代码

var start = 2012;
var end = new Date().getFullYear();
var options = "<option value='' selected>Year</option>";
for(var year = start ; year <=end; year++){
  options += "<option>"+ year +"</option>";
}
document.getElementById("year").innerHTML = options;

<select id="year"></select>

Answer 4

您想在年份的下拉列表中显示默认值。尝试下面的代码，让我知道您是否要这样做！

html代码：

<select id="year"></select>

js代码：

var startYear = 2017;
var endYear = new Date().getFullYear();
var options = "<option selected>"+startYear+"</option>";

for(var year = start + 1; year <= end; year++){
  options += "<option>"+ year +"</option>";
}

document.getElementById("year").innerHTML = options;

Answer 5

如果我正确理解了这个问题，我们想选择当前年份。

var start = 2017;
var end = new Date().getFullYear();
var options = "<option value=''>Year</option>";

for (var year = start; year <= end; year++) {
  var selected = year === end ? " selected" : "";
  options += "<option value=\"" + year + "\"" + selected + ">"+ year +"</option>";
}
document.getElementById("year").innerHTML = options;

如何将默认值添加到动态下拉列表？

5 个答案: