$(function() {
    $(".video_name").each(function() {
        var s = $(this).text();
        $(this).text(cutstr(s, 40));
    });
});
function cutstr(str, len) {
    var str_length = 0;
    var str_len = 0;
    str_cut = new String();
    str_len = str.length;
    for (var i = 0; i < str_len; i++) {
        a = str.charAt(i);
        str_length++;
        if (escape(a).length > 4) {
            //中文字符的长度经编码之后大于4
            str_length++;
        }
        str_cut = str_cut.concat(a);
        if (str_length >= len) {
            str_cut = str_cut.concat("...");
            return str_cut;
        }
    }
    //如果给定字符串小于指定长度，则返回源字符串；
    if (str_length < len) {
        return str;
    }
}