页面刷新后保留JavaScript变量值？

// 存储数据到localStorage
localStorage.setItem("key", "value");

// 从localStorage中获取数据
var value = localStorage.getItem("key");

// 存储数据到sessionStorage
sessionStorage.setItem("key", "value");

// 从sessionStorage中获取数据
var value = sessionStorage.getItem("key");

// 设置Cookie
document.cookie = "key=value; expires=Tue, 19 Jan 2038 03:14:07 UTC; path=/";

// 读取Cookie
var cookies = document.cookie.split(";");
for (var i = 0; i< cookies.length; i++) {
  var cookie = cookies[i].trim();
  if (cookie.indexOf("key=") == 0) {
    var value = cookie.substring("key=".length, cookie.length);
    break;
  }
}