题解 | JS11 模板字符串
const registDate = new Date(person.registTime);
const registMilTime = registDate.valueOf();
const nowMilTime = new Date().valueOf();
const days = Math.floor((nowMilTime - registMilTime) / (1000 * 60 * 60* 24));
const str = `尊贵的牛客网${person.level}级用户${person.name}您好,您已经注册牛客网${days}天啦~`
document.getElementsByTagName('h2')[0].innerText = str;