HTML5サインイン機能

//generate date data
    function buildData() {
        var da = {
            dates: [],//date data, starting from the 1st
            current: '',//the current date
            monthFirst: 1,//Get the 1st day of the month equal to the day of the week
            month: 0,//the current month
            days: 30,//how many days are there in the current month
            day: 0,//how many days is today
            isSigned: false,//whether today has signed in
            signLastDays:3,//consecutive sign-in days
            signToday: function () {
                this.isSigned = true;
                isSigned = true; this.dates[this.day].isSigned = true;
            },
        };
        var ds = [];
        //initialize date data
        var dt = new Date();
        da.current = dt.ToString('yyyy year M month d day');
        da.monthFirst = new Date(dt.getFullYear(), dt.getMonth(), 1).getDay();
        da.month = dt.getMonth() + 1;
        da.days = new Date(dt.getFullYear(), parseInt(da.month), 0).getDate();//get the number of days in the current month
        da.day = dt.getDate();
        for (var i = 1; i < da.days + 1; i++) {
            var o = {
                isSigned: false,//whether signed in
                num: i,//date
                isToday: i == da.day,//whether it is today
                isPass: i < da.day,//time has passed
            };
            ds[i] = o;
        }
        da.dates = ds;
        return da;
    }

 //Render the data
    function renderData(da) {
        var signDays = document.getElementById('spSignDays');
        signDays.innerText = da.signLastDays;
        var root = document.getElementById("signTable");
        root.innerHTML = '';
        var tr, td;
        var st = da.monthFirst;
        var dates = da.dates;
        var rowcount = 0;
        //max 6 rows
        for (var i = 0; i < 42; i++) {
            if (i % 7 == 0) {
                //If there is no more date, break
                if (i > (st + da.days))
                    break;
                tr = document.createElement('tr');
                tr.className = 'darkcolor trb';
                root.appendChild(tr);
                rowcount++;
            }
            // blank in front or behind
            if (i < st || !dates[i - st + 1]) {
                td = document.createElement('td');
                td.innerHTML = '<div class="sign-blank"><span></span></div>';
                tr.appendChild(td);
                continue;
            }
            //fill the number part
            var d = dates[i - st + 1];
            td = document.createElement('td');
            var tdcss = '';
            if (d.isToday)
                tdcss = 'sign-today';
            else if (d.isPass)
                tdcss = 'sign-pass';
            else
                tdcss = 'sign-future';
            if (d.isSigned) {
                tdcss = 'sign-signed ' + tdcss;
                td.innerHTML = '<div class="' + tdcss + '"><span>' + d.num + '</span><svg xmlns="http://www.w3.org/2000/ svg" version="1.1" class="sign-pin svg-triangle "><polygon points="0,0 35,0 0,35" /></svg& gt;</div>';
            } else {
                tdcss = 'sign-unsign ' + tdcss;
                td.innerHTML = '<div class="' + tdcss + '"><span>' + d.num + '</span></div>';
            }
            tr.appendChild(td);
        }
        // Calculate if the last line needs to be added
        if ((st + da.days + 1) / 7 > rowcount)
            root.appendChild(tr);
    }
       // Build the date data
        var da = buildData();
        //render
        renderData(da);