【JavaScript】获取本月第一天和最后一天

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
}
// 自定义格式
console.log(date.getFullYear() + '-' + month + '-' + day)

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
}
// 自定义格式
console.log(endDate.getFullYear() + '-' + endMonth + '-' + endDay)