Date

var d1 = new Date(2015, 4, 31)

var d2 = new Date(2015, 4, 32)

var d3 = new Date(2015, 4, -1)

console.log(d1)

console.log(d2)

console.log(d3)

console.log(d1.getDate(), d1.getMonth() + 1)

console.log(d2.getDate(), d2.getMonth() + 1)

console.log(d3.getDate(), d3.getMonth() + 1)

/*

 Sun May 31 2015 00:00:00 GMT+0800 (中国标准时间)

 Mon Jun 01 2015 00:00:00 GMT+0800 (中国标准时间)

 Wed Apr 29 2015 00:00:00 GMT+0800 (中国标准时间)

 31 5

 1 6

 29 4

*/

 

var d = new Date(2015, -1)

var year = d.getFullYear()

var month = d.getMonth() + 1

var day = d.getDate()

console.log(year, month, day) // 2014 12 1