如何使用JavaScript更改HTML选定选项？

Question

我有这样的选项菜单:

<form name="AddAndEdit">
   <select name="list" id="personlist">
      <option value="11">Person1</option>
      <option value="27">Person2</option>
      <option value="17">Person3</option>
      <option value="10">Person4</option>
      <option value="7">Person5</option>
      <option value="32">Person6</option>
      <option value="18">Person7</option>
      <option value="29">Person8</option>
      <option value="28">Person9</option>
      <option value="34">Person10</option>
      <option value="12">Person11</option>
      <option value="19">Person12</option>
   </select>
</form>

现在我想通过使用href更改所选选项.例如:

<a href="javascript:void(0);"
  onclick="document.getElementById('personlist').getElementsByTagName('option')[11].selected = 'selected';">change</a>

但我想选择选项value=11 (Person1),而不是Person12.

如何更改此代码？

Answer 1

更改

document.getElementById('personlist').getElementsByTagName('option')[11].selected = 'selected'

至

document.getElementById('personlist').value=Person_ID;

Answer 2

以下是用于处理Selectbox的纯JavaScript代码的所有工具:

更新 - 2018年8月28日| Fiddler DEMO

JavaScript代码:

/**
 * Empty Select Box
 * @param eid Element ID
 * @param value text
 * @param text text
 * @author Neeraj.Singh
 */
function emptySelectBoxById(eid, value, text) {
    document.getElementById(eid).innerHTML = "<option value='" + value + "'>" + text + "</option>";
}


/**
 * Reset Select Box
 * @param eid Element ID
 */

function resetSelectBoxById(eid) {
    document.getElementById(eid).options[0].selected = 'selected';
}


/**
 * Set Select Box Selection By Index
 * @param eid Element ID
 * @param eindx Element Index
 */

function setSelectBoxByIndex(eid, eindx) {
    document.getElementById(eid).getElementsByTagName('option')[eindx].selected = 'selected';
    //or
    document.getElementById(eid).options[eindx].selected = 'selected';
}


/**
 * Set Select Box Selection By Value
 * @param eid Element ID
 * @param eval Element Index
 */
function setSelectBoxByValue(eid, eval) {
    document.getElementById(eid).value = eval;
}


/**
 * Set Select Box Selection By Text
 * @param eid Element ID
 * @param eval Element Index
 */
function setSelectBoxByText(eid, etxt) {
    var eid = document.getElementById(eid);
    for (var i = 0; i < eid.options.length; ++i) {
        if (eid.options[i].text === etxt)
            eid.options[i].selected = true;
    }
}


/**
 * Get Select Box Text By ID
 * @param eid Element ID
 * @return string
 */

function getSelectBoxText(eid) {
    return document.getElementById(eid).options[document.getElementById(eid).selectedIndex].text;
}


/**
 * Get Select Box Value By ID
 * @param eid Element ID
 * @return string
 */

function getSelectBoxValue(id) {
    return document.getElementById(id).options[document.getElementById(id).selectedIndex].value;
}

Answer 3

我相信博客发布JavaScript初学者 - 按价值选择下拉选项可能会对您有所帮助.

<a href="javascript:void(0);" onclick="selectItemByValue(document.getElementById('personlist'),11)">change</a>

function selectItemByValue(elmnt, value){

  for(var i=0; i < elmnt.options.length; i++)
  {
    if(elmnt.options[i].value === value) {
      elmnt.selectedIndex = i;
      break;
    }
  }
}

Answer 4

您还可以像这样更改select.options.selectedIndex DOM属性:

function selectOption(index){ 
  document.getElementById("select_id").options.selectedIndex = index;
}

<p>
<select id="select_id">
  <option selected>first option</option>
  <option>second option</option>
  <option>third option</option>
</select>
</p>
<p>
  <button onclick="selectOption(0);">Select first option</button>
  <button onclick="selectOption(1);">Select second option</button>
  <button onclick="selectOption(2);">Select third option</button>
</p>

Answer 5

mySelect

只需执行myValuemyValue等于要将其设置为的选项的value属性的位置.

Answer 6

如果您使用 javascript 添加选项

function AddNewOption(userRoutes, text, id) 
{
    var option = document.createElement("option");
    option.text = text;
    option.value = id;
    option.selected = "selected";
    userdRoutes.add(option);
}

Answer 7

您也可以使用 JQuery

$(document).ready(function () {
  $('#personlist').val("10");
}