获得某月份某日为该年份的第几日

DOCTYPE html >

< html lang= "en" >

< head >

< meta charset= "UTF-8" >

< meta name= "viewport" content= "width=device-width, initial-scale=1.0" >

< meta http-equiv= "X-UA-Compatible" content= "ie=edge" >

< title >Document title >

head >

< body >

< script >

var year = prompt( "输入你的出生年份");

var month = prompt( "输入你出生的月份");

var day = prompt( "输入你的出生日期");

getday( parseInt( year), parseInt( month), parseInt( day));

function getday( year, month, day) {

var sum = 0;

if ( year % 100 == 0 && year % 400 != 0 || year % 4 == 0) {

switch ( month) {

case 1:

sum = day;

break;

case 2:

sum = 31 + day;

break;

case 3:

sum = 60 + day;

break;

case 4:

sum = 91 + day;

break;

case 5:

sum = 121 + day;

break;

case 6:

sum = 152 + day;

break;

case 7:

sum = 182 + day

break;

case 8:

sum = 213 + day;

break;

case 9:

sum = 244 + day;

break;

case 10:

sum = 274 + day;

break;

case 11:

sum = 305 + day;

break;

case 12:

sum = 335 + day;

}

} else {

switch ( month) {

case 1:

sum = day;

break;

case 2:

sum = 30 + day;

break;

case 3:

sum = 59 + day;

break;

case 4:

sum = 90 + day;

break;

case 5:

sum = 120 + day;

break;

case 6:

sum = 151 + day;

break;

case 7:

sum = 181 + day

break;

case 8:

sum = 212 + day;

break;

case 9:

sum = 243 + day;

break;

case 10:

sum = 273 + day;

break;

case 11:

sum = 304 + day;

break;

case 12:

sum = 334 + day;

}

}

alert( "您的生日在第" + year + "年，是第" + sum + "天");

}

< / script >

body >

html >