js超出文字个数展示省略号

方法一：

function wordlimit(cname, wordlength) {
    var cname = document.getElementsByClassName(cname);
    for (var i = 0; i < cname.length; i++) {　　　　　　
        var nowLength = cname[i].innerHTML.length;
        if (nowLength > wordlength) {
            cname[i].innerHTML = cname[i].innerHTML.substr(0, wordlength) + '...';
        }　　　　　　
    }　
};

方法二：

fontNumber (date) {
  const length = date.length
  if (length > 30) {
    var str = ''
    str = date.substring(0, 30) + '......'
    return str
  } else {
    return date
  }
}