JavaScript implements a cookie-based storage class instance

The specific analysis is as follows:

Through this JS class, you can use the same as the session cookie, very simple!

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* * Cookiestorage.js * This class implements the same storage API * as Localstorage and Sessionstorage, which is based on HTTP cookies. */function Cookiestorage (maxage, path) {///two parameters represent storage duration and scope//Get an object to store all cookies var cookies = (function () {//Type description before The GetCookies function var cookies = {}; The object will eventually return var all = Document.cookie; Obtain information about all cookies in the form of a large string if (all = = "")//If the property is a blank return cookie; Returns an empty object var list = All.split (";"); Separation of known/value pairs for (var i = 0; i < list.length; i++) {//traverse each cookie var cookie = list[i]; var p = cookie.indexof ("=");//Find To the first "=" symbol var name = cookie.substring (0,p); Gets the name of the cookie var value = cookie.substring (p+1); Gets the value of the cookie corresponding to = decodeuricomponent (value); Decoding its value cookies[name] = value; Store the name value pair in the object to return cookies; }()); Store the names of all cookies in an array of the var keys = []; for (var key in cookies) Keys.push (key); Now define the storage API public properties and methods//number of cookies stored this.length = keys.length; Returns the name of the nth cookie, and returns null This.key = function (n) {if (N < 0 | | | n >= keys.length) return NULL if n crosses the line keys[n]; }; Returns the cookie value for the specified name, or null This.getitem = function (name) {return Cookies[name] | | null; Store cookie Value This.setitem = function (key, value) {if (!) ( Key in Cookies) {//If the cookie to be contributed does not exist Keys.push (key);//Add the specified name to the array where all the cookie names are stored this.length++;//The number of cookies plus one}//Add the name/ Values are stored in the cookie object for the data. Cookies[key] = value; Start to formally set up cookies. First encode the value of the cookie to be stored//create a string var cookie = key + "=" + encodeuricomponent (value) in the form of "NAME = encoded value"; Add the properties of the cookie to the string if (maxage) cookie + = "; Max-age= "+ maxage; if (path) cookie = "; Path= "+ path; Set the cookie Document.cookie = Cookie by Document.cookie property; }; Deletes the specified cookie This.removeitem = function (key) {if (!) ( Key in the cookie)) return; If the cookie does not exist, do nothing//remove the specified cookie from the internal maintenance cookies Delete Cookies[key]; Also deletes the name in the cookie inside the array. It is simpler to use the array indexof () method defined by ES5. for (var i = 0; i < keys.length i++) {//Traverse all names if (keys[i] = = key) {//When we find the Keys.splice (i,1) we are looking for;//Remove it from the array. Break }} this.length--; Number of cookies minus one//finally by setting the value of the cookie toThe empty string//and the expiration date set to 0来 deletes the specified cookie. Document.cookie = key + "=; Max-age=0 "; }; Remove All Cookies this.clear = function () {//loop all cookies by name and delete cookies for (var i = 0; i < keys.length; i++) document. Cookie = Keys[i] + "=; Max-age=0 "; Resets all internal state cookies = {}; Keys = []; this.length = 0; }; }