/**
 * @param {Number} 想生成的月份
 * @returns {Array} 月份数据
 */
function initMonthDays(currentMonth) {
    let d = new Date()
    d.setMonth(currentMonth - 1) // 设置当前月
    d.setDate(1) // 设置为当月的1号
    let monthList = []
    let count = 0
    let nextMonthCount = 0
    for (let i = 0; i < 6; i++) {
        let weekList = new Array(7);
        if (i === 0) { // 当月第一周
            for (let index = d.getDay() - 1; index < weekList.length; index++) {
                weekList[index] = ++count
            }
        } else { // 剩余的周
            for (let index = 0; index < weekList.length; index++) {
                count++
                if (count <= getDaysOfMonth(d.getMonth())) {
                    weekList[index] = count
                } else { // 补充下个月的号数
                    weekList[index] = ++nextMonthCount
                }
            }
        }
        monthList.push(weekList);
    }

    // 补充上个月的号数
    let preMonthDay = getDaysOfMonth(d.getMonth() - 1)
    for (let index = d.getDay() - 2; index >= 0; index--) {
        monthList[0][index] = preMonthDay--
    }
    return monthList
}


/**
 * @param {Date} currentMonth 当前月份
 * @returns {Number} 当前月的最后一天是多少号
 */
function getDaysOfMonth(currentMonth) {
    let date = new Date()
    date.setMonth(currentMonth + 1)
    date.setDate(0)
    return date.getDate()
}
const monthDaysArr = initMonthDays(3)
console.log(monthDaysArr);