原生JS（cookie操作的封装）

封装cookie的操作：查询cookie个数、查询所有cookie的键、获取cookie、设置cookie、删除cookie、清除全部cookie

/**
* cookieStorage
*/
function cookieStorage( maxage, path ){
var cookie = ( function(){
var cookie = {};
var all = document.cookie;
if( all ==="" ){
return cookie;
}
var list = all.split( "; " );
for( var i=0; i<list.length; i++ ){
var singleCookie = list[i];
var p = singleCookie.indexOf( "=" );
var name = singleCookie.substring( 0, p );
var value = singleCookie.substring( p+1 );
value = decodeURIComponent( value );
cookie[name] = value;
}
return cookie;
}() );

var keys = [];
for( var key in cookie ){
keys.push( key );
}

this.length = keys.length;
this.key = function( n ){
if( n < 0 || n > keys.length-1 ){
return null;
}
return keys[n];
}
this.getItem = function(){
return cookie[name] || null;
}
this.setItem = function( key, value ){
if( !( key in cookie ) ){
keys.push( key );
this.length ++;
}
cookie[key] = value;
var cookie = key + "=" + encodeURIComponent( value );
if( maxage ){
cookie += "; max-age=" + maxage;
}
if( path ){
cookie += "; path=" + path;
}
document.cookie = cookie;
}
this.removeItem = function( key ){
if( !( key in cookie ) ){
return;
}
delete cookie[key];
for( var i=0; i<keys.length; i++ ){
if( keys[i] === key ){
keys.splice( i, 1 );
break;
}
}
this.length--;
document.cookie = key + "=; max-age=0";
}
this.clear = function(){
for( var i=0; i<keys.length; i++ ){
document.cookie = keys[i] + "=; max-age=0";
}
cookie = {};
keys = [];
this.length = 0;
}
}