1.距离生日还有多少天：
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<script>
//给出生日的月份和日期，计算还有多少天过生日
function getDaysToBirthday(month, day) {
var nowTime = new Date();
var thisYear = nowTime.getFullYear();
//今年的生日
var birthday = new Date(thisYear, month - 1, day);
//今年生日已过，则计算距离明年生日的天数
if (birthday < nowTime) {
birthday.setFullYear(nowTime.getFullYear() + 1);
}
var timeDec = birthday - nowTime;
var days = timeDec / (24 * 60 * 60 * 1000);
return Math.ceil(days);
}
getDaysToBirthday(11, 2);
</script>
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2.根据出生年月日，计算年龄:
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<script>
//是否闰年
function isLeap(year){
return (year % 4 === 0 && year % 100 !== 0) || (year % 400 === 0);
}
//根据出生年月日，计算年龄
function getAge(year, month, day) {
//得到当前日期
var nowTime = new Date();
var age = nowTime.getFullYear() - year;//粗略计算出年龄
//若生日是2月29日，且今年不是闰年，则今年生日日期按28日计算
if(month === 2 && day === 29 && !isLeap(nowTime.getFullYear())){
day = 28;
}
//得到今年的生日日期
var nowBirthday = new Date(nowTime.getFullYear(), month - 1, day);
console.log(nowBirthday, nowTime);
if(nowBirthday > nowTime){//若今年的生日没有过，则减一岁
age--;
}
return age;
}
console.log(getAge(2000, 2, 29));
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3.打印当前月份每天的星期：
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<title>Document</title>
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<script>
//获取星期的汉字形式
function getDayOfWeed(i){
var arr = ["一","二","三","四","五","六","日"];
return arr[i];
}
//打印当前月每一天的星期
function printDay(){
var nowTime = new Date();
var year = nowTime.getFullYear();
var month = nowTime.getMonth() + 1;
//得到当前月的总天数
var days = new Date(year, month, 0).getDate();//后一个月份减一天，得到当前月的最后一天的日期
for(var i = 1; i <= days; i++){
console.log(`${year}年${month}月${i}日：星期${getDayOfWeed(new Date(year, month - 1, i).getDay())}`);
}
}
printDay();
</script>
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