function calc(){
var date=new Date(),str
week=date.getDay()
if(week==0){
str="星期日"
}else if(week==1){
str="星期一"
}else if(week==2){
str="星期二"
}else if(week==3){
str="星期三"
}else if(week==4){
str="星期四"
}else if(week==5){
str="星期五"
}else if(week==6){
str="星期六"
}
alert(str)
}
</script>
注意我用的是alert对话框输出的值，new Date()，括号里面可以填指定日期，格式是：YYYY-MM-DD，注意加引号，如果new Date()后面的括号什么都不填，表示获取当前系统的日期和时间,date.getDay()这方法返回的是一个0到6之间的整数，0表示星期天，1到6表示星期一到星期六
方法一：// 计算系统当前是星期几var str = "今天是星期" + "日一二三四五六".charat(new Date().getDay())
方法二：
var a = new array("日", "一", "二", "三", "四", "五", "六")var week = new Date().getDay()var str = "今天是星期"+ a[week]
alert(str)
方法三：
var str = "今天是星期"var week = new Date().getDay()switch (week) {case 0 :
str += "日" break case 1 :
str += "一" break case 2 :
str += "二" break case 3 :
str += "三" break case 4 :
str += "四" break case 5 :
str += "五" break case 6 :
str += "六" break
}
alert(str)
方法四：
var str = ""var week = new Date().getDay()if (week == 0) {
str = "今天是星期日"
} else if (week == 1) {
str = "今天是星期一"
} else if (week == 2) {
str = "今天是星期二"
} else if (week == 3) {
str = "今天是星期三"
} else if (week == 4) {
str = "今天是星期四"
} else if (week == 5) {
str = "今天是星期五"
} else if (week == 6) {
str = "今天是星期六"
}
alert(str)
<!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>
<input id="y" type="text" placeholder="年" /> <input id="m" type="text" placeholder="月" />
<nput id="d" type="text" placeholder="日" /> <br /> <input type="button" id="btn" value="计算星期几" /> <input type="text"
id="w" placeholder="星期几">
<script>
var y = document.getElementById('y')
var m = document.getElementById('m')
var d = document.getElementById('d')
var w = document.getElementById('w')
var btn = document.getElementById('btn')
btn.onclick = function () {
var a = ''
a = y.value + '/' + m.value + '/' + d.value
var date = new Date(a)
var week = ["星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"]
w.value = week[date.getDay()]
}
</script>
</body>
</script>
</body>
</html>
