How to insert dot instead of comma in js keypress

In my website i have textbox that contains 开发者_开发技巧currency amount separeted by dot. Users sometimes press dot on numpad, and that inserts coma in textbox. How can I convert it to dot ? I was trying to do it in keypress event but didn't menage to make it work.

<input type='text' onkeypress='return check(this,event);'>

function check(Sender,e){
  var key = e.which ? e.which : e.keyCode;
  if(key == 44){
     Sender.value += '.';
     return false;
  }
}

UPDATE: This should work if you type anywhere in the input box

function check(Sender,e){
  var key = e.which ? e.which : event.keyCode;
  if(key == 44){
     if (document.selection) { //IE
       var range = document.selection.createRange();
           range.text = '.';
     } else if (Sender.selectionStart || Sender.selectionStart == '0') { 
      var start = Sender.selectionStart;
      var end   = Sender.selectionEnd;
      Sender.value = Sender.value.substring(0, start) + '.' +
           Sender.value.substring(end, Sender.value.length);
      Sender.selectionStart = start+1;
      Sender.selectionEnd   = start+1;     
     } else {
      Sender.value += '.';
     }
     return false;
   }
}

If you're looking to transform a comma character as it is typed, I've answered similar questions on Stack Overflow before:

• Can I conditionally change the character entered into an input on keypress?
• show different keyboard character from the typed one in google chrome

However, I agree with @ChrisF's comment above.

You could do:

$('input').keyup(function(e){
    var code = e.which ? e.which : e.keyCode;
     console.log(code);
    if (code === 110){
        var input = this.value;
        input = input.substr(0, input.length -1);
        console.log(input);
        input += ',';
        this.value = input;        
    }

});

fiddle http://jsfiddle.net/PzgLA/