1.cookie是否有效时间限定？

cookie是有有效时间的，并且可以自定义有效时间

2.如何设置cookie？

这里我是直接封装起来，直接贴代码，不懂可以私信！！！

 // 设置cookie
  static setCookie(key, value, expiremHours) {
    var exdate = new Date();
    exdate.setTime(exdate.getTime() + expiremHours * 60 * 60 * 1000);
    document.cookie =
      key +
      "=" +
      escape(value) +
      (expiremHours == null ? "" : ";expires=" + exdate.toUTCString());
  }

  // 读取cookie
  static getCookie(key) {
    if (document.cookie.length > 0) {
      var c_start = document.cookie.indexOf(key + "=");
      if (c_start != -1) {
        c_start = c_start + key.length + 1;
        var c_end = document.cookie.indexOf(";", c_start);
        if (c_end == -1) c_end = document.cookie.length;
        return unescape(document.cookie.substring(c_start, c_end));
      }
    }
    return "";
  }

  // 删除cookie
  static delCookie(key) {
    var exp = new Date();
    exp.setTime(exp.getTime() - 1);
    var cval = this.getCookie(key);
    if (cval != null) {
      document.cookie = key + "=" + cval + ";expires=" + exp.toUTCString();
    }
  }

  // 节流
  static throttle(callBack, time) {
    let timer = null;
    //timer状态要常驻内存，这里做了一个闭包
    return function() {
      if (!timer) {
        timer = setTimeout(() => {
          callBack();
          timer = null;
        }, time);
      }
    };
  }