JS用函数实现:输入年,月,日,获取这个日期是这一年的第多少天

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<script>
    //输入年,月,日,获取这个日期是这一年的第多少天
    //定义一个函数,
    function isLeapYear(year) {
        return year % 4 ==0 && year % 100 != 0;
    }

    function getDays(year, month, day) {
        //定义一个变量获取天数
        var days = day;
        if (month == 1) {
            return days;
        }//end if
        var monthDay = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
        for (var i=0;i<month-1;i++){
                days+=monthDay[i];
        }// end for
        if(isLeapYear(year)&&month>2){
            days++;
        }
        return days;
    }
    console.log(getDays(2017,3,2));
</script>
</body>
</html>

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转载自blog.csdn.net/qq_37777208/article/details/83590594