格式化输出数字

/******************************************************
*@param object      
*      1.object可以为文本框的对象或文本框的Id
   例如：<input type="text" name="text1" id="value1" value="20.1">
      var elements = document.forms[0].elements;
      formatNumber(elements["text1"],true);
      formatNumber("value1",true);
*    2.object可以为层的Id
   例如：<span id="value">20.1</span>
         formatNumber(value,true);
      formatNumber("value",true);
*@param isShowEmpty 如果对象的值为空，是否显示
*@param precision   显示的小数位数
*/
function formatNumber(object,isShowEmpty,precision){
if(typeof(object) == "string"){  
  object = document.getElementById(object);  
}
if(typeof(object) == "undefined" || object == null){
  alert("The object is not found!");
  return;
}
var value = object.value;
var isFormObject = true;//是否为表单对象
if(typeof(value) == "undefined"){
  value = object.innerText;
  isFormObject = false;
}
if(value == ""){  
  return;
}    
if(typeof(precision) == "undefined"){
  precision = 2;
}
var number = parseFloat(value);        
if(number <= 0 ){
  if(isShowEmpty){
   if(isFormObject){
    object.value = "";
   }else{
    object.innerText = "";
   }
    
  }
  else{  
   var str = "";          
   for(var i = 0; i < precision; i++){
    str += "0";
   }    
   if(isFormObject){
    object.value = "0."+str;
   }else{
    object.innerText = "0." + str;
   }
  }
  return;
}    
if(isFormObject){
  object.value = number.toFixed(precision);
}else{
  object.innerText = number.toFixed(precision);
}
}