Restricting keyboard input with jQuery and validate decimal precision,scale

keycodechecker Demo
txt.Attributes.Add("class", "numbersonly");

In blur or textbox leaving, or in button click call the below function

function IsDecimal(Salary) {
     var _Salary = $('#' + Salary);
     if (!_Salary.isValidScale(6, 2)) {
         _Salary.focus();
         alert('Invalid decimal points');
         return false;
     }
     return true;
 }

/*Numeric validation starts*/

//Allows decimal places with only one .(decimal point or full stop)
$(".numbersonly").keydown(function (event) {
    // Prevent shift key since its not needed
    if (event.shiftKey == true) {
        event.preventDefault();
    }

    // Allow Only: keyboard 0-9, numpad 0-9
    if ((event.keyCode >= 48 && event.keyCode <= 57) || (event.keyCode >= 96 && event.keyCode <= 105)
        //Allow Only: backspace, tab, left arrow, right arrow
        || event.keyCode == 8 || event.keyCode == 9 || event.keyCode == 37 || event.keyCode == 39
        //Allow Only: delete, home, end
        || event.keyCode == 46 || event.keyCode == 36 || event.keyCode == 35
        //Allow Only: .(full stop [keyboar, numpad]) and check if there is more than one .(full stop)
        || ((event.keyCode == 190 || event.keyCode == 110) && $(this).val().indexOf('.') < 0)
    ) {
        // Allow normal operation
    } else {
        // Prevent the rest
        event.preventDefault();
    }
});

//Validate the count of precision and scale of a decimal value
//ctrlID.isValidScale(6,2);
jQuery.fn.isValidScale = function (precision, scale) {
    //return !Number.isNaN(num) && parseFloat(num).toFixed(scale).toString() === this.val();
    /*          debugger;
         var ina = !isNaN(num);
         var len = decimalPlaces(num)
         var isTrue = decimalPlaces(num) <= parseInt(scale)
         var tr = !isNaN(num) && isTrue;*/

    var num = parseFloat(this.val()) || 0;
    var intPart = parseInt(this.val()).toString(); //Convert to string

    //if input control is empty
    if (num.length == 0) return true;
    if (intPart.length > parseInt(precision)) return false;

    return !isNaN(num) && decimalPlaces(num) <= parseInt(scale);
};

function decimalPlaces(n) {
    var a;
    var len = (a = (n.toString().charAt(0) == '-' ? n - 1 : n + 1).toString().replace(/^-?[0-9]+\.?([0-9]+)$/, '$1').length) >= 1 ? a : 0;
    return parseInt(len);
}

$(".intonly").keydown(function (event) {
    // Prevent shift key since its not needed
    if (event.shiftKey == true) {
        event.preventDefault();
    }
    // Allow Only: keyboard 0-9, numpad 0-9, backspace, tab, left arrow, right arrow, delete, home, end
    if ((event.keyCode >= 48 && event.keyCode <= 57) || (event.keyCode >= 96 && event.keyCode <= 105) || event.keyCode == 8 || event.keyCode == 9 || event.keyCode == 37 || event.keyCode == 39 || event.keyCode == 46 || event.keyCode == 36 || event.keyCode == 35) {
        // Allow normal operation
    } else {
        // Prevent the rest
        event.preventDefault();
    }
});

var isValidCurrency = function (input) {
    var num = parseFloat(input);
    return !Number.isNaN(num) && parseFloat(num).toFixed(2).toString() === input;
};
/*Numeric validation ends*/