Question

单击按钮后，我尝试更改下拉文本。改变位置可能是一个更好的选择，但我不确定如何尝试。每当我将下拉列表的值更改为新文本或尝试时，下拉列表会在第一行显示空白文本时应显示＆＃34;选择一组现有查询结果：＆＃34;。

HTML：

<select id="asset" class="titilium" 
    selectedIndex="{{currentIndex}}" 
    value="{{dropDownValue}}" 
    on-change="{{changedHandler}}" required>
  <option selected disabled value="">Select an existing set of query results:</option>
  <option value="Placeholder">Placeholder</option>
  <option value="Placeholder A">Placeholder A</option>
  <option value="Placeholder B">Placeholder B</option>
  <option value="Placeholder C">Placeholder C</option>
  <option value="Placeholder D">Placeholder D</option>
  <option value="Placeholder E">Placeholder E</option>
  <option value="Placeholder F">Placeholder F</option>
  <option value="Placeholder G">Placeholder G</option>
  <option value="Placeholder H">Placeholder H</option>
  <option value="Placeholder I">Placeholder I</option>
</select>

飞镖：

 var dropDownValue = shroot.querySelector("#asset");

resetBtn.onClick.listen((e) {
  dropDownValue.value = "Select an existing set of query results:";
});

Answer 1

您已将""定义为此行的值。如果要重置<select>元素，则必须设置此值

<option selected disabled value="">Select an existing set of query results:</option>
                                ^^

如下所示的按钮点击处理程序会重置您的选择。

void clickHandler(Event event) {
  $['asset'].value = "";
}

简单的Google Dart DropDown价值变动

1 个答案: