How to allow numeric (0-9) & decimal value textbox using jQuery?

You could remove the non numeric char when keyup.

$("#txtQty").keyup(function() {
    var $this = $(this);
    $this.val($this.val().replace(/[^\d.]/g, ''));        
});​

The demo.

You cant use e.preventDefault() it on the keyup event. Change it to keydown.

$(function () {
    $("input[id*='txtQty']").keydown(function (event) {


        if (event.shiftKey == true) {
            event.preventDefault();
        }

        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 == 190) {

        } else {
            event.preventDefault();
        }

        if($(this).val().indexOf('.') !== -1 && event.keyCode == 190)
            event.preventDefault(); 
        //if a decimal has been added, disable the "."-button

    });
});​

Fiddle