function checkNum(e) {         var re = /^\d+(?=\.{0,1}\d+$|$)/         if (e.value != "") {             if (!re.test(e.value)) {                 alert("请输入正确的数字");                 e.value = "";                 e.focus();             }         }         e.value = parseFloat(e.value).toFixed(1);     } 

 

function checkNum(e) {

         var re = /^\d+(?=\.{0,1}\d+$|$)/

         if (e.value != "") {

             if (!re.test(e.value)) {

                 alert("请输入正确的数字");

                 e.value = "";

                 e.focus();

             }

         }

         e.value = parseFloat(e.value).toFixed(1);

     }

 

<input style="width:50px" id="txtDelayDeduction" οnblur="checkNum(this)"  οnkeyup="this.value=this.value.replace(/[^0-9.]/g,'')"  type="textbox">