js 限制只能输入数字小数点

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" onblur="checkNum(this)"  onkeyup="this.value=this.value.replace(/[^0-9.]/g,'')"  type="textbox">

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" onblur="checkNum(this)" 
onkeyup="this.value=this.value.replace(/[^0-9.]/g,'')"  type="textbox">