//短信字数限制    
function textCounter(obj, showid, maxlimit) {    
    var len = strLen(obj.value);    
    var showobj = document.getElementById(showid);    
    if(len > maxlimit) {    
        obj.value = getStrbylen(obj.value, maxlimit);    
        showobj.innerHTML = '0';    
    } else {    
        showobj.innerHTML = maxlimit - len;    
    }    
    if(maxlimit/2 - len > 0) {    
        showobj.parentNode.style.color = "";    
    } else {    
        showobj.parentNode.style.color = "red";    
    }    
        
}    
function getStrbylen(str, len) {    
    var num = 0;    
    var strlen = 0;    
    var newstr = "";    
    var obj_value_arr = str.split("");    
    for(var i = 0; i < obj_value_arr.length; i ++) {    
        if(i < len && num + byteLength(obj_value_arr[i]) <= len) {    
            num += byteLength(obj_value_arr[i]);    
            strlen = i + 1;    
        }    
    }    
    if(str.length > strlen) {    
        newstr = str.substr(0, strlen);    
    } else {    
        newstr = str;    
    }    
    return newstr;    
}    
function byteLength (sStr) {    
    aMatch = sStr.match(/[^\x00-\x80]/g);    
    return (sStr.length + (! aMatch ? 0 : aMatch.length));    
}    
function strLen(str) {    
    var charset = document.charset;     
    var len = 0;    
    for(var i = 0; i < str.length; i++) {    
        len += str.charCodeAt(i) < 0 || str.charCodeAt(i) > 255 ? (charset == "utf-8" ? 2 : 1) : 1;    
    }    
    return len;    
}