JavaScript截断字符串

JavaScript截断字符串，类似于substr()，只不过这个函数不会截断单词，在发生截断后，会添加一个省略号

if (!function_exists('subsent')) {
 
   function subsent($string, $start = 0, $length = 0, $cap = '...') {
 
      if ($length <= 0 || strlen($string) < $length) { return $string; }
 
      $string = substr($string, $start, strpos($string, ' ', $length)) . ' ' . $cap;
 
      return $string;
 
   }
 
}