js+cookie判断下载

// 设置Cookie
function setCookie(name, value, days) {
    var expires = "";
    if (days) {
        var date = new Date();
        date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
        expires = "; expires=" + date.toUTCString();
    }
    document.cookie = name + "=" + (value || "") + expires + "; path=/";
}

// 获取Cookie
function getCookie(name) {
    var nameEQ = name + "=";
    var ca = document.cookie.split(';');
    for (var i = 0; i < ca.length; i++) {
        var c = ca[i];
        while (c.charAt(0) == ' ') c = c.substring(1, c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length, c.length);
    }
    return null;
}

// 判断是否已下载
function hasDownloaded(filename) {
    var downloaded = getCookie("downloaded_" + filename);
    return downloaded === "true";
}

// 标记为已下载
function markAsDownloaded(filename) {
    setCookie("downloaded_" + filename, "true", 7); // 设置有效期为7天
}

// 使用示例
var filename = "example.pdf";
if (!hasDownloaded(filename)) {
    // 执行下载操作
    window.location.href = "/path/to/" + filename;
    markAsDownloaded(filename); // 标记为已下载
} else {
    alert("您已经下载过此文件。");
}