javascript - 更改选择值 Javascript

Question

我有一个用以下数据动态填充 JSON 数据的选择:元素、1、2、3 ...一旦选择，该选择就会隐藏，因为再次显示按钮，但我无法使用元素值，它与用户选择的值一起显示，我如何更改 JavaScript 中选择的值？HTML

 <div id="tablaSelect">
    <table id=tabla2 style="width:80%" >
    <tr>  
      <th>
        <div class="styled-select">
          <select class="select" id="boards">
          </select>
        </div>
     </th>
    </tr>
   </table>

Javascript 选择:

$('#boards')
  .append($("<option></option>")
  .attr("value",'')
  .text("Eelement")); 

$.each(boards, function(index, value) {
     $('#boards')
        .append($("<option></option>")
        .attr("value",value.id)
        .text(value.name)); 
     arrayBoards.push(value.id);
});

要改变的Javascript

function cambiar(){
     document.getElementById("tablaSelect").style.display="block";
     document.getElementById("select").value = '';
}

Answer 1

如果有一个具有该值的选项(查看您的代码，确实存在)，您的 document.getElementById("select").value = ''; 就会起作用，但是 元素的 id 是 boards，而不是 select:

$('#boards')
  .append($("<option></option>")
  .attr("value",'')
  .text("Eelement"));

var boards = [
  {id: 1, name: "One"},
  {id: 2, name: "Two"},
  {id: 3, name: "Three"},
  {id: 4, name: "Four"}
];
var arrayBoards = [];

$.each(boards, function(index, value) {
     $('#boards')
        .append($("<option></option>")
        .attr("value",value.id)
        .text(value.name)); 
     arrayBoards.push(value.id);
});

function cambiar(value){
     document.getElementById("tablaSelect").style.display="block";
     document.getElementById("boards").value = value;
}

cambiar("1");
setTimeout(function() {
  cambiar("");
}, 800);

<div id="tablaSelect">
  <table id=tabla2 style="width:80%" >
  <tr>  
    <th>
      <div class="styled-select">
        <select class="select" id="boards">
        </select>
      </div>
   </th>
  </tr>
 </table>
</div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

或者，因为您使用的是 jQuery，所以使用它的 val : $("#boards").val("");

$('#boards')
  .append($("<option></option>")
  .attr("value",'')
  .text("Eelement"));

var boards = [
  {id: 1, name: "One"},
  {id: 2, name: "Two"},
  {id: 3, name: "Three"},
  {id: 4, name: "Four"}
];
var arrayBoards = [];

$.each(boards, function(index, value) {
     $('#boards')
        .append($("<option></option>")
        .attr("value",value.id)
        .text(value.name)); 
     arrayBoards.push(value.id);
});

function cambiar(value){
     document.getElementById("tablaSelect").style.display="block";
     $("#boards").val(value);
}

cambiar("1");
setTimeout(function() {
  cambiar("");
}, 800);

<div id="tablaSelect">
  <table id=tabla2 style="width:80%" >
  <tr>  
    <th>
      <div class="styled-select">
        <select class="select" id="boards">
        </select>
      </div>
   </th>
  </tr>
 </table>
</div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>