JavaScript Cookie Operations Detailed introduction

Keep in mind that cookies are a string property of a document. To save a cookie, simply create a string, the format is name=<value> (name = value), and then set the document's Document.cookie to be equal to it. For example, if you want to save the user name that the form receives, the code looks like this:

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Document.cookie = "username" + Escape (form.username.value);

It is important to use the escape () function here because the cookie value may contain semicolons, commas, or spaces. This means that when reading the cookie value, the corresponding unescape () function must be used to decode the value.

We also have to introduce four properties of cookies. These attributes are appended to the string value in the following format:

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name=<value>[; expires=<date>][; domain=<domain>][; path=<path>][; Secure]

Name =< value >[; expires=< date >][; domain=< domain >][; path=< path >][; security]

<value>, <date>, <domain> and <path> should be replaced with corresponding values. <date> You should use the GMT format to get the date value of this GMT format using the date class dated. toGMTString () method of the JavaScript scripting language. The square brackets represent this item to be optional. For example, the square brackets on both sides of the [; secure] will need to be set to make the cookie safe; Secure "is appended to the cookie string value. If "; Secure "is not added to the cookie string, then this cookie is not secure. Do not add angle brackets <> and brackets [] to cookies (unless they are the contents of certain values). When you set properties, you do not have properties that can be set in any order.

1, GetCookie (name)

Gets the cookie value, the parameter name is the cookie name.

2, Setcookie (name, value)

Set the cookie value to set the cookie value for name.

3, Deletecookie (name)

Deletes the cookie value for name.

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/** Get Cookies */ Get the value of a cookie The following describes how to get the value of a cookie. The value of a cookie can be obtained directly by Document.cookie: var Strcookie=document.cookie; This will get a string of multiple name/value pairs separated by semicolons that include all cookies under that domain name. For example: <script language= "JavaScript" type= "Text/javascript" > <!-- Document.cookie= "userid=828"; Document.cookie= "Username=hulk"; var Strcookie=document.cookie; alert (Strcookie); --> </script> function GetCookie (name) { var arg = name + "="; var alen = Arg.length; var clen = document.cookie.length; var i = 0; while (I < Clen) { var j = i + Alen; if (Document.cookie.substring (i, j) = = arg) return Getcookieval (j); i = Document.cookie.indexOf ("", I) + 1; if (i = = 0) break; } return null; } /** Set Cookies */ function Setcookie (name, value) { var argv = setcookie.arguments; var argc = SetCookie.arguments.length; var expires = (argc > 2)? ARGV[2]: null; var path = (argc > 3)? ARGV[3]: null; var domain = (argc > 4)? ARGV[4]: null; var secure = (argc > 5)? ARGV[5]: false; Document.cookie = name + "=" + Escape (value) + ((expires = null)? "" : ("; Expires= "+ expires.togmtstring ())) + ((path = null)? "" : ("; Path= "+ path)) + (domain = null)? "" : ("; domain= "+ domain)" + (Secure = = True)? "; Secure ":" "); } /** Delete Cookies */ function Deletecookie (name) { var exp = new Date (); Exp.settime (Exp.gettime ()-1); var cval = 0; Document.cookie = name + "=" + Cval + "; Expires= "+ exp.togmtstring (); } function Getcookieval (offset) { var endstr = document.cookie.indexOf (";", offset); if (endstr = = 1) endstr = document.cookie.length; Return unescape (document.cookie.substring (offset, endstr)); }