Copy only numbers from textbox using javascript

 In this Example i am Describing , Copy only numbers or numeric characters in the text box..
here if we copy characters + numbers it will copy only Numbers

Here is the Example :

1)Copy data from Textbox :

2) Paste in another Textbox :

3) Final OUTPUT :

TextBox oncopy :

oncopy="return CopyNumericOnly(this);"

Script :

function CopyNumericOnly(obj) {
            var textboxvalue = obj.value;
            var strValidChars = "0123456789";
            var strChar;
            var FilteredChars = "";
            for (d = 0; d < textboxvalue.length; d++) {
                strChar = textboxvalue.charAt(d);
                if (strValidChars.indexOf(strChar) != -1) {
                    FilteredChars = FilteredChars + strChar;
                }
            }
            window.clipboardData.setData('Text', FilteredChars);
            return false;
        }