Native Js implementation of calendar widget

/*****************************
 * Calendar style corresponding table* #date calendar block* table table* th header* td body* a.now this month* a.non-arrival other months* a.day today* a.href link* #date_diglogs remember dialog****************************/
 
#date {
 width: 220px;
 padding-bottom: 5px;
 box-shadow: 0 1px 3px #ccc;
 border: 1px solid #EDEDED;
}
 
#date table {
 width: inherit;
 user-select: none;
 font-size: 12px;
 border-collapse: collapse;
 border-spacing: 0px;
}
 
#date table tr th {
 background-color: #f8f8f8;
 color: #5e5f63;
}
 
#date table tr:nth-of-type(2) th {
 font-weight: 300;
}
 
#date table tr td {
 text-align: center;
 font-family: "Comic Sans MS";
 padding: 2px 0;
}
 
#date table tr td a {
 text-decoration: none;
}
 
#date table tr td a.now {
 color: #757575;
}
 
#date table tr td a.day {
 background: mediumblue;
 text-decoration: underline;
 color: #fff;
}
 
#date table tr td a.href {
 border: 1px solid #ccc;
 transition: all 1s linear;
}
 
#date table tr td a.href:hover {
 border: 1px dotted #5E5F63;
 background: gold;
}
 
#date table tr td a.non-arrival {
 color: #ccc;
} 
 
.date_diglogs {
 font-size: 10px;
 background: #fff;
 padding: 2px 5px;
 border-radius: 3px;
 box-shadow: 0 1px 3px #ccc;
 border: 1px solid #EDEDED;
 color: #757575;
}

/* 2021/2/26
 * Function: Calendar pendant* Qingyuan Miaoshan*/
 
function BlogDate(nowDate) {
 /* Variable data */
 this.year = nowDate.getFullYear(); // Get the yearthis.month = nowDate.getMonth(); // Get the monththis.day = nowDate.getDate(); // Get what day it is todaythis.week = new Date(this.year, this.month, 1).getDay(); // Get the number of free days at the beginning of each monththis.days = new Date(this.year, this.month + 1, -1).getDate() + 1; // Get the total number of daysthis.last_month = new Date(this.year, this.month, -1).getDate() + 1; // Save the number of days in last month/* unchanged data*/
 this.now_year = nowDate.getFullYear(); // Save this year's year this.now_month = nowDate.getMonth(); // Save this year's month }
 
BlogDate.prototype.createDate = function(name) {
 // Get blocks and create tables let date_div = document.getElementById('date');
 let date_table = document.createElement('table');
 date_div.appendChild(date_table);
 
 // Create all tr ​​tags let date_all_tr = new Array();
 for (let n = 0; n < 8; n++) {
 date_all_tr[n] = document.createElement('tr');
 date_table.appendChild(date_all_tr[n]);
 }
 
 // Create the head th tag let date_head_th = new Array();
 for (let n = 0; n < 3; n++) {
 date_head_th[n] = document.createElement('th');
 date_all_tr[0].appendChild(date_head_th[n]);
 }
 
 // Set special element attributes date_head_th[0].setAttribute('id', 'prev');
 date_head_th[1].setAttribute('colspan', '5');
 date_head_th[1].setAttribute('title', `${name}`);
 date_head_th[2].setAttribute('id', 'next');
 
 // Create the week th label let date_week_th = new Array();
 for (let n = 0; n < 7; n++) {
 date_week_th[n] = document.createElement('th');
 date_all_tr[1].appendChild(date_week_th[n]);
 }
 
 // Create body td, a tag array let date_body_td = new Array();
 let date_body_td_a = new Array();
 
 // Create body td, a tag entity for (let n = 2, i = 0; n < 8; n++, i++) {
 date_body_td[i] = [];
 date_body_td_a[i] = [];
 
 for (let m = 0; m < 7; m++) {
 date_body_td[i][m] = document.createElement('td');
 date_body_td_a[i][m] = document.createElement('a');
 date_body_td[i][m].appendChild(date_body_td_a[i][m]);
 date_all_tr[n].append(date_body_td[i][m]);
 }
 }
}
 
BlogDate.prototype.setBlogDate = function(newDate) {
 /* Update data */
 this.year = newDate.getFullYear(); // Get the yearthis.month = newDate.getMonth(); // Get the monththis.day = newDate.getDate(); // Get today's datethis.week = new Date(this.year, this.month, 1).getDay(); // Get the number of free days at the beginning of each monththis.days = new Date(this.year, this.month + 1, -1).getDate() + 1; // Get the total number of daysthis.last_month = new Date(this.year, this.month, -1).getDate() + 1; // Get the number of days in last month}
 
BlogDate.prototype.updateTime = function(blogs_date) {
 // Get the calendar object let date_div = document.getElementById('date');
 let date_table = date_div.getElementsByTagName('table')[0];
 
 // Create calendar header tr, th
 let date_head_tr = date_table.getElementsByTagName('tr')[0];
 let date_head_th = date_head_tr.getElementsByTagName('th');
 
 // Create header data let date_head_arr = [
 '<', `${this.year} year ${this.month + 1} month`, '>'
 ];
 
 // Update header data for (let n = 0; n < date_head_th.length; n++) {
 date_head_th[n].textContent = date_head_arr[n];
 }
 
 // Create the week part tr, th
 let date_week_tr = date_table.getElementsByTagName('tr')[1];
 let date_week_th = date_week_tr.getElementsByTagName('th');
 
 // Create week data let date_week_arr = [
 'Sun', 'Mon', 'Tues', 'Wed', 'Thurs', 'Fri', 'Sat'
 ];
 
 // Update week data for (let n = 0; n < date_week_th.length; n++) {
 date_week_th[n].textContent = date_week_arr[n];
 }
 
 // Get the a tag of body td let date_body_td_a = date_table.getElementsByTagName('a');
 
 // Set the number of days in other months (front)
 for (let n = this.week - 1, last_month = this.last_month; n >= 0; n--, last_month--) {
 date_body_td_a[n].textContent = last_month;
 date_body_td_a[n].setAttribute('class', 'non-arrival');
 }
 
 // Set the number of days in the current month (current)
 for (let n = this.week, i = 1; i <= this.days; n++, i++) {
 date_body_td_a[n].textContent = i;
 // If it is this day of this month, set the day style, otherwise set the now style if ((i == this.day) &&
 (new Date(this.year, this.month, 1).getMonth() == this.now_month) &&
 (new Date(this.year, this.month, 1).getFullYear() == this.now_year)) {
 date_body_td_a[n].setAttribute('class', 'day');
 } else {
 date_body_td_a[n].setAttribute('class', 'now');
 }
 }
 
 // Set the number of days in other months (later)
 for (let n = this.week + this.days, i = 1; n < date_body_td_a.length; n++, i++) {
 date_body_td_a[n].textContent = i;
 date_body_td_a[n].setAttribute('class', 'non-arrival');
 }
 
 // If the date data in the link part is the same, set the corresponding style for (let n = 0; n < date_body_td_a.length; n++) {
 for (let m = 0; m < blogs_date.href_num; m++) {
 if ((this.year == blogs_date.href_year[m]) &&
 (this.month + 1 == blogs_date.href_month[m]) &&
 (n == blogs_date.href_day[m])) {
 date_body_td_a[n].setAttribute('href', blogs_date.href_url[m]);
 date_body_td_a[n].classList.add('href');
 date_body_td_a[n].setAttribute('target', '_blank');
 } else {
 // If not, determine whether there are redundant attributes if (Boolean(date_body_td_a[n].getAttribute('target')) &&
 Boolean(date_body_td_a[n].getAttribute('href')) &&
 (date_body_td_a[n].getAttribute('class') == 'now' ||
 date_body_td_a[n].getAttribute('class') == 'non-arrival')) {
 date_body_td_a[n].removeAttribute('href');
 date_body_td_a[n].removeAttribute('target');
 }
 }
 }
 }
}
 
function initDate(
 // Default calendar parameter table blogs_date = {
 blogs_name: 'My Calendar',
 href_year: [2021],
 href_month: [2],
 href_day: [26],
 href_url: ['http://www.4399.com/'],
 href_prompt: ['This is the calendar widget I wrote'],
 href_dialog: false,
 href_num: undefined
 }
) {
 // Are the parameter lengths equal if ((blogs_date.href_day.length != blogs_date.href_month.length) ||
 (blogs_date.href_month.length != blogs_date.href_year.length) ||
 (blogs_date.href_year.length != blogs_date.href_url.length)) {
 console.info('Calendar parameter lengths are not equal');
 return false;
 }
 // The parameter lengths are the same, set the corresponding length else {
 blogs_date.href_num = blogs_date.href_day.length;
 }
 
 // Create calendar data let timeDate = new Date();
 let blogDate = new BlogDate(timeDate);
 
 // Create calendar entity blogDate.createDate(blogs_date.blogs_name);
 blogDate.updateTime(blogs_date);
 
 // Add prev event document.getElementById('prev').onclick = function() {
 timeDate.setMonth(timeDate.getMonth() - 1);
 blogDate.setBlogDate(timeDate);
 blogDate.updateTime(blogs_date);
 }
 
 // Add next event document.getElementById('next').onclick = function() {
 timeDate.setMonth(timeDate.getMonth() + 1);
 blogDate.setBlogDate(timeDate);
 blogDate.updateTime(blogs_date);
 }
 
 openDialogs(blogs_date);
 
 showBlogsData(blogs_date, timeDate);
}
 
function showBlogsData(blogs_date, now) {
 for (let k in blogs_date) {
 console.info(`[${k}] : ${blogs_date[k]}`);
 }
 console.info(`BlogsDate Ok ${now}`);
}
 
function openDialogs(blogs_date) {
 // Whether to open the dialog switch (blogs_date.href_dialog) {
 case true:
 let hrefId = document.getElementsByClassName('href');
 for (let n = 0; n < hrefId.length; n++) {
 hrefId[n].onmouseover = function(e) {
 if (this.getAttribute('class') != 'now' &&
 this.getAttribute('class') != 'non-arrival') {
 
 var e = e || window.event;
 
 let x = e.clientX;
 let y = e.clientY;
 
 let prompt = blogs_date.href_prompt[n];
 let dialogs = document.createElement('div');
 
 dialogs.classList.add('date_diglogs');
 dialogs.textContent = prompt;
 dialogs.style.cssText = `position: absolute;
 left: ${x-20}px;
 top: ${y+20}px`;
 
 document.body.appendChild(dialogs);
 }
 }
 hrefId[n].onmouseout = function() {
 if (this.getAttribute('class') != 'now' &&
 this.getAttribute('class') != 'non-arrival') {
 
 let diglogs = document.getElementsByClassName('date_diglogs')[0];
 document.body.removeChild(diglogs);
 }
 }
 }
 break;
 case false:
 break;
 }
}

<!DOCTYPE html>
<html>
 <head>
 <meta charset="utf-8">
 <title>date html</title>
 <link rel="stylesheet" href="date.css" media="screen">
 </head>
 <body>
 <h3>Hello</h3>
 <div id="date"></div>
 <script src="date.js"></script>
 <script>
 initDate(blogs_date = {
 blogs_name : 'My Calendar',
 href_year : [2021, 2021], 
 href_month : [2, 2], 
 href_day : [27, 3], 
 href_url : ['http://www.4399.com/', 'http://www.baidu.com/'],
 href_prompt: ['I have to go out to see my family today', 'I have to go to bed early today'],
 href_dialog: true
 });
 </script>
 </body>
</html>