document.cookie = ‘name=‘+‘username‘;
    document.cookie = ‘value=‘+‘value1‘;

    var cookarr = document.cookie.replace(/\s/g,"").split(‘;‘);//將cookie的空格全部替換掉，不然會出現空格，使結果無法判斷
    var havcome = false;
    for (var i=0;i<cookarr.length;i++){
        var str = cookarr[i].split(‘=‘);
        if(str[0]==‘dateam‘) {
            havcome 
 
= true;
            break
        }
    }
    console.log(document.cookie);
    console.log(havcome);
    var date = new Date();
    var day = date.getTime();
    console.log(day);
    var newday = new Date(day + 7*24*60*60*1000);//設置過期時間，這裏設置為七天之後；
    var oldday = new Date(day -1);//設置刪除時間，只要過期時間在設置時間之前，就可以將cookie刪除；
 

    console.log(newday.toUTCString());
    if (!havcome){
        document.cookie = ‘dateam‘+‘=‘+‘haha‘+‘;expires=‘+newday.toUTCString();
        alert(‘歡迎你第一次來‘);
    }

    document.cookie = ‘dateam‘+‘=‘+‘haha‘+‘;expires=‘+oldday.toUTCString();//將過期時間設置為已經過去的 1 ms，則可以立即刪除dateamcookie

js 操作cookie，getCookie,setCookie ,removeCookie