September 2022
Intermediate to advanced
585 pages
8h 17m
Chinese
Content preview from JavaScript 经典实例：第三版
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：在第二个标签页中显示存储在 sessionStorage 和 cookie 中的数据
在新标签页窗口中，
cookie
和
localStorage
的值依然存在，因为
cookie
是针对会
话的，而
sessionStorage
针对标签页窗口，不持久存储。
上述两幅截图展示了跨标签页持久存储的差别，这是
sessionStorage
和
cookie
之
间除了在
JavaScript
中存取方式不同之外的另一个重要区别。但愿上述示例和两幅
截图也表明了
sessionStorage
的潜在危害，尤其是在已经使用
cookie
的情况下。
如果网站或应用的用户习惯了跨标签页窗口持久存储的
cookie
，
sessionStorage
的行为会让人感到意外。除了这种行为上的差异，还有一点要注意：浏览器中删除
cookie
的菜单选项可能对
sessionStorage
没有影响，这也有可能让用户大失所望。
抛开这些问题，
sessionStorage
还是有一定用途的，如果只想在特定的标签页窗口
中存储数据，
sessionStorage
是不错的选择。
最后，请注意
sessionStorage
的实现：
sessionStorage
和
localStorage
（下一节
介绍）都包含在
W3C DOM
Storage
规范中。二者都是
window
对象的属性，因此
可以全局访问。而且二者都是
Storage
对象的具体实现，如果修改
Storage
原型，
sessionStorage
和
localStorage
都
受影响。
Storage.prototype.someMethod ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.