javascript - onchange 和 Select 不起作用

Question

我正在尝试运行该函数，但我不确定如何让它运行。我尝试单击并为每个选择创建单独的函数。我想要该函数做的就是当我选择将段落的值更改为下面的选项的选项时。请帮忙。

<select id="Providers"  onchange="ProviderChanger()">
    <option value="Empty" id="Empty" name="Empty">Please Select     Provider</option> 
    <option value="Du1" id="Du1" name="Du1">Du 052</option>
    <option value="Du2" id="Du2" name="Du2">Du 055</option>
    <option value="Etisilat1" name="Etisilat1" id="Etisilat1">Etisilat 050</option>
    <option value="Etisilat2" name="Etisilat2" id="Etisilat2">Etisilat 056</option>
    <option value="Office" name="Office" id="Office">House/Office 04</option>
</select>

function ProviderChanger()
{
  var ProviderValue = document.getElementById("Provider").value;
  alert(ProviderValue);
  if (ProviderValue == "Du1")
    document.getElementById("Provider").innerHTML = "+971-55";
  else if (ProviderValue == "Du2")
    document.getElementById("Provider").innerHTML = "+971-52";
  else if (ProviderValue == "Etisilat1")
    document.getElementById("Provider").innerHTML = "+971-50";
  else if (ProviderValue == "Etisilat2")
    document.getElementById("Provider").innerHTML = "+971-56";
  else if (ProviderValue == "Office")
    document.getElementById("Provider").innerHTML = "+971-04";
  else
    document.getElementById("Provider").innerHTML = "";
}

Answer 1

这不应该是:

var ProviderValue = document.getElementById("Provider").value;

是这样的:

var ProviderValue = document.getElementById("Providers").value;