javascript获取价值onchange

Question

我试图获取选择的输入值以在div onchange中显示，但它似乎不起作用，我只是想知道有人可以提供帮助还是知道原因？

function getData(dropdown) {
  var values = dropdown.options[dropdown.selectedIndex].value;
  var pop = Game.currentGame.ui.options.servers.values.population;
  var servers = document.getElementsByClassName('hud-intro-guide')[0];
  servers.textContent = "Server " + pop + " population"
}

<select class="hud-intro-server" onchange="getData(this);">
  <optgroup label="asia servers">
    <option value="v8617903">asia #1 </option>
    <option value="v8617895">asia #2 </option>
    <option value="v8617899">asia #3 </option>
    <option value="v8617900">asia #4 </option>
    <option value="v8617898">asia #5 </option>
    <option value="v8617894">asia #6 </option>
    <option value="v8617901">asia #7 </option>
    <option value="v8617902">asia #8 </option>
    <option value="v8617897">asia #9 </option>
  </optgroup>
</select>

<div class="hud-intro-guide"> </div>

Answer 1

var pop = Game.currentGame.ui.options.servers.values.population;

应该是

var pop = Game.currentGame.ui.options.servers[values].population;

Answer 2

可能您的问题与您如何尝试使用变量values有关。

  var pop = Game.currentGame.ui.options.servers.values.population;
                                                ^
                                                |
                                                +-- Here you're accessing the attribute values 
                                                    rather than getting the server related 
                                                    to the chosen option.

您真正想要的是以下内容：

function getData(dropdown) {
  var values = dropdown.options[dropdown.selectedIndex].value;
  var pop = Game.currentGame.ui.options.servers[values].population; 
                                                ^
                                                |
                                                +-- With this, you're getting the server.

  var servers = document.getElementsByClassName('hud-intro-guide')[0];
  servers.textContent = "Server " + pop + " population"
}

Answer 3

您不需要在选择标签上添加更改事件。只需在document的jquery函数中的select上添加change事件。readyevent编写如下：

$('#your select id').on('change', function() {  alert( this.value );});

OR

 $('.your select class').on('change', function() {  alert( this.value );});