1.函数的定义和使用:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>if...else
</title>
<script type="text/javascript">
var ticket = true;
if (ticket) {
document.write("有票,看电影")
} else{
document.write("没有票,看不了电影")
}
function add(a,b) {
var sum = 0;
sum = a + b;
alert(sum);
}
add(4,3);
add(2,4);
alert(5,7);
</script>
</head>
<body>
</body>
</html>
2.函数的调用:
<!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>函数调用</title> <script type="text/javascript"> function tcon() { alert("恭喜你学会函数调用了!"); } </script> </head> <body> <form> <input type="button" value="点点我" onclick="tcon()"> </form> </body> </html>
3.函数的返回值:
<!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>返回值函数</title> <script type="text/javascript"> function app2(x,y) { var sum,x,y; sum = x * y; return sum; } var req1 = app2(5,6); var req2 = app2(2,3); var sumq = req1 + req2; document.write("req1的值:"+req1+"<br/>"); document.write("req2的值:"+req2+"<br/>"); document.write(req1+"与"+req2+"和:"+sumq); </script> </head> <body> </body> </html>
原文：http://www.cnblogs.com/pengsi/p/6366345.html