var showLength = 17 ; // 表示文字数

onload = function() {
  elements = document.getElementsByTagName("*") ;
  for (var i = 0; i < elements.length; ++i)
	with (elements[i])
	  if (className == "length" && innerHTML.length > showLength)
		innerHTML = innerHTML.substr(0, showLength) + '...' ;
}