function onlyNumeric(field)
{
  streng = field.value;
  oldvalue = streng;
  newstreng = '';
  for (i = 0; i < streng.length; i++)
  {
    thischar = field.value.substring(i, i+1)
    if (thischar == '1' || thischar == '2' || thischar == '3' || thischar == '4' || thischar == '5' || thischar == '6' || thischar == '7' || thischar == '8' || thischar == '9' || thischar == '0')
      newstreng = newstreng + streng.substring(i, i+1);
  }

  if((typeof varOnlyTalError)=="string")
  {
    if (oldvalue != newstreng) {
      tmpvarOnlyTalError=varOnlyTalError;
      tmpvarOnlyTalError=tmpvarOnlyTalError.replace(/\$tekst\$/gi,oldvalue)
      alert(tmpvarOnlyTalError);
    }
  }

  field.value = newstreng;
}