写入cookie的JavaScript代码库cookieLibrary.js_javascript技巧

Also, this version adds optional path and domain parameters to
the DeleteCookie function. If you specify a path and/or domain
when creating (setting) a cookie**, you must specify the same
path/domain when deleting it, or deletion will not occur.

The FixCookieDate function must now be called explicitly to
correct for the 2.x Mac date bug. This function should be
called *once* after a Date object is created and before it
is passed (as an expiration date) to SetCookie. Because the
Mac date bug affects all dates, not just those passed to
SetCookie, you might want to make it a habit to call
FixCookieDate any time you create a new Date object:

var theDate = new Date();
FixCookieDate (theDate);

Calling FixCookieDate has no effect on platforms other than
the Mac, so there is no need to determine the user's platform
prior to calling it.

This version also incorporates several minor coding improvements.

**Note that it is possible to set multiple cookies with the same
name but different (nested) paths. For example:

SetCookie ("color","red",null,"/outer");
SetCookie ("color","blue",null,"/outer/inner");

However, GetCookie cannot distinguish between these and will return
the first cookie that matches a given name. It is therefore
recommended that you *not* use the same name for cookies with
different paths. (Bear in mind that there is *always* a path
associated with a cookie; if you don't explicitly specify one,
the path of the setting document is used.)

Revision History:

"Toss Your Cookies" Version (22-Mar-96)
- Added FixCookieDate() function to correct for Mac date bug

"Second Helping" Version (21-Jan-96)
- Added path, domain and secure parameters to SetCookie
- Replaced home-rolled encode/decode functions with Netscape's
new (then) escape and unescape functions

"Free Cookies" Version (December 95)

For information on the significance of cookie parameters, and
and on cookies in general, please refer to the official cookie
spec, at:

http:www.netscape.com/newsref/std/cookie_spec.html

****************************************************************** */

/**//* "Internal" function to return the decoded value of a cookie */
代码如下:
function getCookieVal (offset) {
var endstr = document.cookie.indexOf (";", offset);
if (endstr == -1) {
endstr = document.cookie.length;
}
return unescape(document.cookie.substring(offset, endstr));
}

/**//* Function to correct for 2.x Mac date bug. Call this function to
fix a date object prior to passing it to SetCookie.
IMPORTANT: This function should only be called *once* for
any given date object! See example at the end of this document. */
代码如下:
function FixCookieDate (date) {
var base = new Date(0);
var skew = base.getTime(); // dawn of (Unix) time - should be 0
if (skew > 0) { // except on the Mac - ahead of its time
date.setTime(date.getTime() - skew);
}
}

/**//* Function to return the value of the cookie specified by "name".
name - String object containing the cookie name.
returns - String object containing the cookie value, or null if
the cookie does not exist. */
代码如下:
function GetCookie (name) {
var temp = name + "=";
var tempLen = temp.length;
var cookieLen = document.cookie.length;
var i = 0;
while (i < cookieLen) {
var j = i + tempLen;
if (document.cookie.substring(i, j) == temp) {
return getCookieVal(j);
}
i = document.cookie.indexOf(" ", i) + 1;
if (i == 0) break;
}
return null;
}

/**//* Function to create or update a cookie.
name - String object containing the cookie name.
value - String object containing the cookie value. May contain
any valid string characters.
[expiresDate] - Date object containing the expiration data of the cookie. If
omitted or null, expires the cookie at the end of the current session.
[path] - String object indicating the path for which the cookie is valid.
If omitted or null, uses the path of the calling document.
[domain] - String object indicating the domain for which the cookie is
valid. If omitted or null, uses the domain of the calling document.
[secure] - Boolean (true/false) value indicating whether cookie transmission
requires a secure channel (HTTPS).

The first two parameters are required. The others, if supplied, must
be passed in the order listed above. To omit an unused optional field,
use null as a place holder. For example, to call SetCookie using name,
value and path, you would code:

SetCookie ("myCookieName", "myCookieValue", null, "/");

Note that trailing omitted parameters do not require a placeholder.

To set a secure cookie for path "/myPath", that expires after the
current session, you might code:

SetCookie (myCookieVar, cookieValueVar, null, "/myPath", null, true); */
代码如下:
function SetCookie (name,value,expiresDate,path,domain,secure) {
document.cookie = name + "=" + escape (value) +
((expiresDate) ? "; expires=" + expiresDate.toGMTString() : "") +
((path) ? "; path=" + path : "") +
((domain) ? "; domain=" + domain : "") +
((secure) ? "; secure" : "");
}

/**//* Function to delete a cookie. (Sets expiration date to start of epoch)
name - String object containing the cookie name
path - String object containing the path of the cookie to delete. This MUST
be the same as the path used to create the cookie, or null/omitted if
no path was specified when creating the cookie.
domain - String object containing the domain of the cookie to delete. This MUST
be the same as the domain used to create the cookie, or null/omitted if
no domain was specified when creating the cookie. */
代码如下:
function DeleteCookie (name,path,domain) {
if (GetCookie(name)) {
document.cookie = name + "=" +
((path) ? "; path=" + path : "") +
((domain) ? "; domain=" + domain : "") +
"; expires=Thu, 01-Jan-70 00:00:01 GMT";
}
}

// Calling examples:
// var expdate = new Date ();
// FixCookieDate (expdate); // Correct for Mac date bug - call only once for given Date object!
// expdate.setTime (expdate.getTime() + (24 * 60 * 60 * 1000)); // 24 hrs from now
// SetCookie ("ccpath", "http://www.dupcit.com/articles/", expdate);
// SetCookie ("ccname", "WebWoman", expdate);
// SetCookie ("tempvar", "This is a temporary cookie.");
// SetCookie ("ubiquitous", "This cookie will work anywhere in this domain",null,"/");
// SetCookie ("paranoid", "This cookie requires secure communications",expdate,"/",null,true);
// SetCookie ("goner", "This cookie must die!");
// document.write (document.cookie + "
");
// DeleteCookie ("goner");
// document.write (document.cookie + "
");
// document.write ("ccpath = " + GetCookie("ccpath") + "
");
// document.write ("ccname = " + GetCookie("ccname") + "
");
// document.write ("tempvar = " + GetCookie("tempvar") + "
");

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