function getCookie(cname) {
    let name = cname + "=";
    let ca = document.cookie.split(‘;‘);
    for (let i = 0; i < ca.length; i++) {
        let c = ca[i].trim();
        if (c.indexOf(name) == 0) return c.substring(name.length, c.length);
    }
    return "";
}

function deleteCookie(cname) {
    let d = new Date();
    let expires = "expires=" + d.toGMTString();
    document.cookie = cname + "=; " + expires;
}

function setCookie(cname, cvalue, exdays) {
    let d = new Date();
    d.setTime(d.getTime() + (exdays * 24 * 60 * 60 * 1000));
    let expires = "expires=" + d.toGMTString();
    document.cookie = cname + "=" + cvalue + "; " + expires;
}

javascript cookie 操作