How Do I Validate Floating Point Number which will have two decimal points?

// Allocation Percentage text-box allow numeric and allow 2 decimal points only
 function extractNumber(obj, decimalPlaces, allowNegative) {
     var temp = obj.value;

     // avoid changing things if already formatted correctly
     var reg0Str = '[0-9]*';
     if (decimalPlaces > 0) {
         reg0Str += '\[\,\.]?[0-9]{0,' + decimalPlaces + '}';
     } else if (decimalPlaces < 0) {
         reg0Str += '\[\,\.]?[0-9]*';
     }
     reg0Str = allowNegative ? '^-?' + reg0Str : '^' + reg0Str;
     reg0Str = reg0Str + '$';
     var reg0 = new RegExp(reg0Str);
     if (reg0.test(temp)) return true;

     // first replace all non numbers
     var reg1Str = '[^0-9' + (decimalPlaces != 0 ? '.' : '') + (decimalPlaces != 0 ? ',' : '') + (allowNegative ? '-' : '') + ']';
     var reg1 = new RegExp(reg1Str, 'g');
     temp = temp.replace(reg1, '');

     if (allowNegative) {
         // replace extra negative
         var hasNegative = temp.length > 0 && temp.charAt(0) == '-';
         var reg2 = /-/g;
         temp = temp.replace(reg2, '');
         if (hasNegative) temp = '-' + temp;
     }

     if (decimalPlaces != 0) {
         var reg3 = /[\,\.]/g;
         var reg3Array = reg3.exec(temp);
         if (reg3Array != null) {
             // keep only first occurrence of .
             //  and the number of places specified by decimalPlaces or the entire string if decimalPlaces < 0
             var reg3Right = temp.substring(reg3Array.index + reg3Array[0].length);
             reg3Right = reg3Right.replace(reg3, '');
             reg3Right = decimalPlaces > 0 ? reg3Right.substring(0, decimalPlaces) : reg3Right;
             temp = temp.substring(0, reg3Array.index) + '.' + reg3Right;
         }
     }

     obj.value = temp;
 }
 function blockNonNumbers(obj, e, allowDecimal, allowNegative) {
     var key;
     var isCtrl = false;
     var keychar;
     var reg;
     if (window.event) {
         key = e.keyCode;
         isCtrl = window.event.ctrlKey
     }
     else if (e.which) {
         key = e.which;
         isCtrl = e.ctrlKey;
     }

     if (isNaN(key)) return true;

     keychar = String.fromCharCode(key);

     // check for backspace or delete, or if Ctrl was pressed
     if (key == 8 || isCtrl) {
         return true;
     }

     reg = /\d/;
     var isFirstN = allowNegative ? keychar == '-' && obj.value.indexOf('-') == -1 : false;
     var isFirstD = allowDecimal ? keychar == '.' && obj.value.indexOf('.') == -1 : false;
     var isFirstC = allowDecimal ? keychar == ',' && obj.value.indexOf(',') == -1 : false;
     return isFirstN || isFirstD || isFirstC || reg.test(keychar);
 }
 function blockInvalid(obj) {
     var temp = obj.value;
     if (temp == "-") {
         temp = "";
     }

     if (temp.indexOf(".") == temp.length - 1 && temp.indexOf(".") != -1) {
         temp = temp + "00";
     }
     if (temp.indexOf(".") == 0) {
         temp = "0" + temp;
     }
     if (temp.indexOf(".") == 1 && temp.indexOf("-") == 0) {
         temp = temp.replace("-", "-0");
     }
     if (temp.indexOf(",") == temp.length - 1 && temp.indexOf(",") != -1) {
         temp = temp + "00";
     }
     if (temp.indexOf(",") == 0) {
         temp = "0" + temp;
     }
     if (temp.indexOf(",") == 1 && temp.indexOf("-") == 0) {
         temp = temp.replace("-", "-0");
     }
     temp = temp.replace(",", ".");
     obj.value = temp;
 }

<asp:TextBox ID="txtAllocationPercentage" runat="server" CssClass="textbox" ToolTip="Enter Allocation Percentage"
                                            onblur="extractNumber(this,2,true);blockInvalid(this);" onkeyup="extractNumber(this,2,true);" 
                                            onKeyPress="return blockNonNumbers(this, event, true, true);"></asp:TextBox>