setForm

setForm是一個很好用的function，所以把他從YAHOO.util.Connect給抽出來了，他的作用就是：給他一個form的id，他會把form裡面所有的form element的key value給組合成request str。
demo:http://chunghe.googlecode.com/svn/trunk/experiment/setForm.htm

function setForm(formId){  
 var oForm;
 if(typeof formId == 'string'){
  // Determine if the argument is a form id or a form name.
  // Note form name usage is deprecated, but supported
  // here for backward compatibility.
  oForm = (document.getElementById(formId) || document.forms[formId]);
 }
 else if(typeof formId == 'object'){
  // Treat argument as an HTML form object.
  oForm = formId;
 }
 else{
  return;
 }
 var hasSubmit = false;
 var sFormData = '';
 for (var i=0; i<oForm.elements.length; i++){
  oElement = oForm.elements[i];
  oDisabled = oElement.disabled;
  oName = oElement.name;
  oValue = oElement.value;

  // Do not submit fields that are disabled or
  // do not have a name attribute value.
  if(!oDisabled && oName)
  {
   switch(oElement.type)
   {
    case 'select-one':
    case 'select-multiple':
     for(var j=0; j<oElement.options.length; j++){
      if(oElement.options[j].selected){
       if(window.ActiveXObject){
        sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oElement.options[j].attributes['value'].specified?oElement.options[j].value:oElement.options[j].text) + '&';
       }
       else{
        sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oElement.options[j].hasAttribute('value')?oElement.options[j].value:oElement.options[j].text) + '&';
       }
      }
     }
     break;
    case 'radio':
    case 'checkbox':
     if(oElement.checked){
      sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oValue) + '&';
     }
     break;
    case 'file':
     // stub case as XMLHttpRequest will only send the file path as a string.
    case undefined:
     // stub case for fieldset element which returns undefined.
    case 'reset':
     // stub case for input type reset button.
    case 'button':
     // stub case for input type button elements.
     break;
    case 'submit':
     if(hasSubmit === false){
      if(this._hasSubmitListener && this._submitElementValue){
       sFormData += this._submitElementValue + '&';
      }
      else{
       sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oValue) + '&';
      }

      hasSubmit = true;
     }
     break;
    default:
     sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oValue) + '&';
   }
  }
 }
 
 sFormData = sFormData.substr(0, sFormData.length - 1);
 return sFormData;

}