js获取本月第一天和最后一天，获取当前月份(亲测可用)

js获取当前月份第一天：

        var date = new Date();
        date.setDate(1);
        var month = parseInt(date.getMonth()+1);
        var day = date.getDate();
        if (month < 10) {
            month = '0' + month
        }
        if (day < 10) {
            day = '0' + day
        }
        console.log(date.getFullYear() + '-' + month + '-' + day)
        // 格式：2020-01-01

js获取当前月份最后一天：

        var endDate=new Date();
        var currentMonth=endDate.getMonth();
        var nextMonth=++currentMonth;
        var nextMonthFirstDay=new Date(endDate.getFullYear(),nextMonth,1);
        var oneDay=1000*60*60*24;
        var lastTime = new Date(nextMonthFirstDay-oneDay);
        var endMonth = parseInt(lastTime.getMonth()+1);
        var endDay = lastTime.getDate();
        if (endMonth < 10) {
            endMonth = '0' + endMonth
        }
        if (endDay < 10) {
            endDay = '0' + endDay
        }
        console.log(endDate.getFullYear() + '-' + endMonth + '-' + endDay)
        //格式：2020-12-30