Cookie(也)是JavaScript中的一种机制,可以实现严格的跨页面全局变量的要求。
Cookie是存于用户硬盘的一个文件,这个文件通常对应于一个域名,当浏览器再次访问这个域名时,便使这个cookie可用。因此,cookie可以跨越一个域名下的多个网页,但不能跨越多个域名使用。
在Cookie设置中,用escape()函数进行编码,可避免乱码和特殊字符问题; 当使用escape()编码后,在取出值以后需要使用unescape()进行解码才能得到原来的cookie值。
设置Cookie时可以直接给document.cookie赋值:
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而且后面的值不会覆盖前面的值,它具有一种累加机制。
cookie的值可以由document.cookie直接获得,但这样获取的是所有的cookie值;要通过一指定cookie名称来获得所对应的值,则需做一些处理。
构造通用的cookie处理函数:
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下面我来编写一个登录函数,加强理解和应用
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调用(或称 嵌入)以上Js代码的页面文件,如下:
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页面效果 如下所示:
前面讲到
“
设置Cookie时,可以直接给 document.cookie 赋值:
document.cookie="userId=828";
document.cookie="userName=hulk";
而且后面的值不会覆盖前面的值,它具有一种 累加机制。
”
Page2.html内部页面(你可以先这样理解),必须在登录后才能使用。该页面需要对用户当前PC的Cookie进行判断,如果发现用户已经通过该机器登录过,该页面则显示 欢迎信息,否则显示“请登录”的链接。
Page2.html页面的代码如下(下面分开说明):
(1) Js代码 (通用读取Cookie方法):
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(2) Page2.html HTML 代码部分:
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另外,关于删除Cookie,可以使用以下方法:
该函数可以删除指定名称的cookie:
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