用Javascript操作Cookie

转自：http://www.codebit.cn/pub/html/javascript/tip/javascript_cookie/

Cookie 是维护客户端状态的解决方案之一，在大多数服务器端语言中都提供了对 Cookie 直接操作的函数，在客户端，我们可以用  javascript 来实现对 Cookie 的操作。本文介绍的就是用 Javascript 操作 Cookie 的方法。三个函数中 getCookie() 是获取Cookie值， setCookie() 是设置Cookie值，deleteCookie() 是删除Cookie。 

// 说明：用 Javascript 操作 Cookie
// 整理：http://www.CodeBit.cn 

function setCookie( name, value, expires, path, domain, secure ) {

    var today = new Date();
    today.setTime( today.getTime() );
    if ( expires ) {
        expires = expires * 1000 * 60 * 60 * 24;
    }

    var expires_date = new Date( today.getTime() + (expires) );

    document.cookie = name+'='+escape( value ) +
        ( ( expires ) ? ';expires='+expires_date.toGMTString() : '' ) + //expires.toGMTString()
        ( ( path ) ? ';path=' + path : '' ) +
        ( ( domain ) ? ';domain=' + domain : '' ) +
        ( ( secure ) ? ';secure' : '' );

} 


function getCookie( name ) {

    var start = document.cookie.indexOf( name + "=" );
    var len = start + name.length + 1;

    if ( ( !start ) && ( name != document.cookie.substring( 0, name.length ) ) ) {
        return null;
    }

    if ( start == -1 ) return null;

    var end = document.cookie.indexOf( ';', len );

    if ( end == -1 ) end = document.cookie.length;
        return unescape( document.cookie.substring( len, end ) );
    } 

window.onload = function(){
    var dateStrInCookie = getCookie("today");
    
    
    if ( dateStrInCookie == null )
    {
        setTimeout(function(){
            //do some job
            alert("once per day!");
        },5*1000);
        
        setCookie("today", new Date().toLocaleDateString());
    }
}

function deleteCookie( name, path, domain ) {
    if ( getCookie( name ) ) 
        document.cookie = name + '=' +
        ( ( path ) ? ';path=' + path : '') +
        ( ( domain ) ? ';domain=' + domain : '' ) +
        ';expires=Thu, 01-Jan-1970 00:00:01 GMT';
}