为什么 JavaScript 不设置 h:inputHidden 值？ [复制]

Question

我看到了很多例子，也做了同样的事情，但我不能用 JavaScript 设置值。

这是我的代码

<h:form id="listPlacesForm">
  <h:inputHidden id="hiddenMapCenter" value="#{userPlaces.center}" />
</h:form>

和 JavaScript

if (navigator.geolocation) {
    navigator.geolocation.getCurrentPosition(findPosition);
} else
    error('Geo Location is not supported');

function findPosition(position) {
    var lat = position.coords.latitude;
    var lng = position.coords.longitude;
    alert('Start')
    var str = lat + ", " + lng;
    var elem = document.getElementById('listPlacesForm:hiddenMapCenter')
    alert(str)
    elem.value = 'asfsf'
    alert('It works!' + str);
}

所有这些代码都有效，除了行：elem.value = 'asfsf'
我试过了：elem.value = 'sfd'，elem.value = "asfd"，elem.value = str

有什么想法吗？

更新 1
生成的 HTML

<form id="mainTabId:listPlacesForm" 
      name="mainTabId:listPlacesForm" method="post"
      action="/DarkComm/app/settings?execution=e3s1" enctype="application/x-www-form-urlencoded">
      <input type="hidden" name="mainTabId:listPlacesForm" value="mainTabId:listPlacesForm" />
      <input id="mainTabId:listPlacesForm:hiddenMapCenter"
             type="hidden"          
             name="mainTabId:listPlacesForm:hiddenMapCenter" value="" />
    <input type="hidden"   name="javax.faces.ViewState"
           id="javax.faces.ViewState" value="e3s1" />
</form>

Answer 1

改变这个：

      var elem = document.getElementById('listPlacesForm:hiddenMapCenter')

到这里：

      var elem = document.getElementById('hiddenMapCenter')