// 文字数オーバー時のトリミング関数

function cutStringById(id, size) {
  var str = document.getElementById(id).innerHTML;
  if(str.length > size){
    document.getElementById(id).innerHTML = str.substring(0, size) + rest;
  }
}
 
function cutStringByTagNameAndClassName(tagName, className, size) {
  var elements = document.getElementsByTagName(tagName);
  for (i=0; i < elements.length; i++) {
    if (elements[i].className == className) {
      var str = elements[i].innerHTML;
      elements[i].innerHTML = trim(str,size);
    }
  }
}
 
function cutStringByIdAndTagName(id, tagName, size) {
  var element = document.getElementById(id);
  var elements = element.getElementsByTagName(tagName);
  for (i=0; i < elements.length; i++) {
    var str = elements[i].innerHTML;
    if(str.length > size){
      elements[i].innerHTML = trim(str,size);
    }
  }
}
 
function cutStringByClassNameAndTagName(className, tagName, size) {
  var elements = document.getElementsByTagName(tagName);
  for (i=0; i < elements.length; i++) {
    if (elements[i].parentNode.className == className) {
      var str = elements[i].innerHTML;
      elements[i].innerHTML = trim(str,size);
    }
  }
}
 
function trim(str, size) {
  if(str.length > size){
    var cutstring = str.substring(0, size);
    var byte = countByte(cutstring);
    var tmp = "";
    if (byte < size*2) {
       for(k=0; k < (size*2-byte)*2; k++){
         tmp = str.substring(0,size + k);
         if (countByte(tmp) >= size*2) {
           break;
         }
       }
    }
    if(tmp){
      return tmp + rest;
    } else {
      return str.substring(0, size) + rest;
    }
  } else {
    return str;
  }
}
 
function countByte(str) {
  var byte = 0;
  for (j=0; j < str.length; j++) {
    str.charCodeAt(j) < 0x100 ? byte++ : byte += 2;
  }
  return byte;
}