javascript - js month switching, please give me ideas or code

Question

// 时间切换
private tabTime(num: number) {
    let self = this;

    let now = new Date();
    let arr = [];

    if (num > 0) {
        this.num2 ++;
    }
    if (num < 0) {
        this.num2 --;
    }

    let b = Number(now.getMonth());

    now.setMonth(b + Number(this.num2)); // 输出时间

    let newA = now.getFullYear();
    let newB: any = Number(now.getMonth());
    let newC: any = now.getDay();
    newB = ((newB + 1) < 10 ? "0" : "") + (newB + 1);
    let y = newA + ' - ' + (newB);
    this.currMonthData = y;

    let days = this.getEveryMonthDays(newA, newB);

    this.StartTimeStamp = Number(newA + newB + "01");
    this.CurrTimeStamp = Number(newA + newB + days);

    this.loadChart(this.StartTimeStamp, this.CurrTimeStamp);

}

Answer 1

If month represents the current month, use new Date(year, month-1) to get the previous/next month, new Date(year, month, 0) to get the last day of the previous month, new Date(year, month, 1) Get the first day of the current month, new Date(year, month+1, 0) gets the last day of the current month (that is, the total number of days in the current month). Then use these values ​​to calculate the number of days in the month after switching and the number of indented days before the first week, and finally render them