/**
  * 
  * @param strpara 要截取的出字符串
  * @param limitLength 截取的长度
  * @param hasDot 是否要加"..."
  * @return 
*/
function subStrByLength(str, len, hasDot) 
{ 
    var newLength = 0; 
    var newStr = ""; 
    var chineseRegex = /[^\x00-\xff]/g; 
    var singleChar = ""; 
    var strLength = str.replace(chineseRegex,"**").length; 
    for(var i = 0;i < strLength;i++){ 
        singleChar = str.charAt(i).toString(); 
        if(singleChar.match(chineseRegex) != null){ 
            newLength += 2; 
        }else{ 
            newLength++; 
        } 
        if(newLength > len){ 
            break; 
        } 
        newStr += singleChar; 
    } 
    if(hasDot && strLength > len) 
    { 
        newStr += "..."; 
    } 
    return newStr; 
}