javaScript基础-函数-案例：输出今天是今年的第多少天

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>计算今天是今年的第多少天</title>
</head>
<body>
<script>
    var date = new Date();
    var year = date.getFullYear();
    var month = date.getMonth()+1;
    var day = date.getDate();
    getDate(year,month,day);
    //得到天数
    function getDate(year,month,day) {
        //定义变量天数
        var days = day;
        var months = [31,28,31,30,31,30,31,31,30,31,30,31];
        for(var i = 0 ; i < month - 1 ; i ++){
            days += months[i];
        }
        if( isLeapYear(year) && month>2){
            days++;
        }
        document.write(year+"年已经过去"+days+"天") ;
    }
    //判断是否为闰年
    function  isLeapYear(year) {
        return  year%4 == 0 && year%100 != 0 ||year % 400 == 0;
    }


</script>
</body>
</html>

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