Javascript 操作 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。以下是javascript操作cookie的几个方法:

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 ) );
}

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() : '' ) + ( ( path ) ? ';path=' + path : '' ) + ( ( domain ) ? ';domain=' + domain : '' ) + ( ( secure ) ? ';secure' : '' ); 
}

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';
}