1、函数（保留两个小数

function checkNum(obj){
     obj.value = obj.value.replace(/[^\d.]/g,"");     
     obj.value = obj.value.replace(/^\./g,"");     
     obj.value = obj.value.replace(/\.{2,}/g,"."); 
     obj.value = obj.value.replace(".","$#$").replace(/\./g,"").replace("$#$",".");     
     obj.value = obj.value.replace(/^(\-)*(\d+)\.(\d\d).*$/,'$1$2.$3');     
 }

2、在input的keyup事件中使用

<td >
  <input type="text" name="price" value="${storeProdute.retail_price }" id="price" size="5" style="text-align: right;"  οnkeyup="checkNum(this)">             
</td>