如何保留选择默认选项

Question

我有一个选择html元素多年，我希望它的默认值仅是“年”，但是我的js代码正在重写它。 我该怎么办？

<select id="f_year" name="f_year">
    <option disabled selected value>年</option>
</select>

<script>
var start = 1900;
    var end = new Date().getFullYear();
    var options = "";
    for(var year = start ; year <=end; year++){
        options += "<option>"+ year +　"年" + "</option>";
    }
    document.getElementById("f_year").innerHTML = options;
</script>

Answer 1

当您重新创建选择选项时。 代替keepin var options = ""; 将其保留为var options = "<option disabled selected value>年</option>";

<select id="f_year" name="f_year">

</select>

<script>
var start = 1900;
    var end = new Date().getFullYear();
    var options = "<option disabled selected value>年</option>";
    for(var year = start ; year <=end; year++){
        options += "<option>"+ year +　"年" + "</option>";
    }
    document.getElementById("f_year").innerHTML = options;
</script>

Answer 2

最好在可能的情况下将HTML保留在HTML中……
…所以，我只用+=而不是=附加您的options 。

在有效的代码段中查看：

 var start = 1900; var end = new Date().getFullYear(); var options = ""; for (var year = start; year <= end; year++) { options += "<option>" + year +  "年" + "</option>"; } document.getElementById("f_year").innerHTML += options; // TAKIT: Modified only here! 

 <select id="f_year" name="f_year"> <option disabled selected value>年</option> </select> 

希望能帮助到你。