function isCharsInBag (s, bag)
{ 
  var i,c;
  for (i = 0; i < s.length; i++)
  {  
        c = s.charAt(i);//字符串s中的字符
    if (bag.indexOf(c) > -1)
        return c;
  }
  return "";
}
检查函数:
function ischinese(s)
{
var errorChar;
var badChar = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789><,[]{}?/+=|//'/":;~!#$%()`";
     errorChar = isCharsInBag( s, badChar)
        if (errorChar != "" )
    {
        report=report+"请重新输入中文/n";
        return false;
    }    
   
    return true;
}