1：html注释：
<html>
<body>
<script type="text/javascript">
<!--
document.write("Hello World!");
//两个正斜杠是 JavaScript 的注释符号，它会阻止 JavaScript 编译器对这一行的编译-->
</script>
</body>
</html>
2：支持三元运算符
greeting=(visitor=="PRES")?"Dear President ":"Dear ";
3：三种消息框
警告框：alert("text")
确认框：confirm("text")
提示框：prompt("noon",12)
4：类似python的for in
var x
var mycars = new Array()
mycars[0] = "Saab"
mycars[1] = "Volvo"
mycars[2] = "BMW"
for (x in mycars)
{
document.write(mycars[x] + "<br />")
}
5：异常处理
<html>
<body>
<script type="text/javascript">
while(true){
var x=prompt("Enter a number between 0 and 10:","")
try
{
if(x>10)
throw "Err1"
else if(x<0)
throw "Err2"
else
break
}
catch(er)
{
if(er=="Err1")
alert("Error! The value is too high")
if(er == "Err2")
alert("Error! The value is too low")
}}
</script>
</body>
</html
6：显示时间
<html>
<head>
<script type="text/javascript">
function startTime()
{
var today=new Date()
var h=today.getHours()
var m=today.getMinutes()
var s=today.getSeconds()
// add a zero in front of numbers<10
m=checkTime(m)
s=checkTime(s)
document.getElementById(‘txt‘).innerHTML=h+":"+m+":"+s
t=setTimeout(‘startTime()‘,500)
}
function checkTime(i)
{
if (i<10)
{i="0" + i}
return i
}
</script>
</head>
<body >
<div id="txt"></div>
</body>
</html>
javascript：入门笔记
时间： 2024-08-04 13:10:42