JavaScript Digital input box

Limit the input box can only enter numbers,

You can also use document.execCommand ( "Undo"), is available, but a little too complicated logic, without the familiar command, equal to the program buried in a mine

Can also be directly input into the type of number, although it may be non-numeric input of existence, but to meet the normal use, it does not require complex database and interface design, to intercept illegal characters

Here to do a cleanup operation directly, you can design complex, return to the previous state

          thisObj.find("#userName").bind("onafterpaste keyup",function (evt) {
            var my = $(this), v = my.val();
            if(isNaN(v)){
              my.val(v.replace(/[^\d]/g,''));
            }
          });