leetcod-刷题系列-一年中的第几天

/**
@params {string} date
@return {number}
*/
var dayOfYear = function(date) {
 let ymd = date.split('-')
	let y = +ymd[0]
	let m = +ymd[1]
	let d = +ymd[2]
	let monthDay = [31,28,31,30,31,30,31,31,30,31,30,31]
	if((y%4 === 0 && y%100 !== 0) || y%400 ===0){
	 monthDay[1] = 29
	}
	let num = 0
	for(let i = 0;i < m -1;i++){
	 num+=monthDay[i]
	}
	return num+d
};