Javascript document.cookie 究竟是如何工作的？
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How exactly does document.cookie work?
提问by Hyman M
If I get Chrome to show me document.cookieby going into the console and typing document.cookie;it'll give me, say:
如果我document.cookie通过进入控制台并输入document.cookie;它来让 Chrome 向我展示，它会给我，说：
"name=John; gender=male";
"name=John; gender=male";
But then if I type in, say, document.cookie = 5;all it does is add 5;to the start of the string, so I get:
但是如果我输入，比如说，document.cookie = 5;它所做的就是添加5;到字符串的开头，所以我得到：
"5; name=John; gender=male";
"5; name=John; gender=male";
If I try document.cookie = null;then it doesn't even do anything.
如果我尝试，document.cookie = null;它甚至不会做任何事情。
How can this be? It's a variable, isn't it? So why isn't the assignment operator working the way it should? Is it actually just a bit of syntactic sugar rather than a real variable? And if so, what precisely is the sugar covering up?
怎么会这样？这是一个变量，不是吗？那么为什么赋值运算符没有按照它应该的方式工作呢？它实际上只是一些语法糖而不是真正的变量吗？如果是这样，糖究竟掩盖了什么？
采纳答案by T.J. Crowder
document.cookiehas veryspecial behavior. As you've seen, assigning to it adds(or updates) a cookie (or multiple cookies), rather than replacingall of the cookies. It's very unusual.
document.cookie有非常特殊的行为。如您所见，分配给它会添加（或更新）一个 cookie（或多个 cookie），而不是替换所有 cookie。这是非常不寻常的。
Read all about it on MDN.
在MDN上阅读所有相关信息。
回答by Alexander Gessler
The string on the right side of the assignment operator to document.cookiesshould be a semicolon separated list of key-value pairs, i.e. document.cookie = "aKey=5"will set/update the aKeycookie.
赋值运算符 to 右侧的字符串document.cookies应该是一个以分号分隔的键值对列表，document.cookie = "aKey=5"即将设置/更新aKeycookie。
So yes, document.cookieshows special behavior.
所以是的，document.cookie表现出特殊的行为。
