js绑定事件2种方法：
1. <input type = "button" onclick="clickHandler()">
2. 该方法必须掌握
<input type = "button" id="button1">
<script type = "text/javascript">
var v = document.getElementById("button1");
v.onclick=clickHandler; //注意，没有括号
</script>
<!DOCTYPE html>
<html>
<head>
<title>js16.html</title>
</head>
<body>
<script type="text/javascript">
function getEvent(event)//event是浏览器自动生成的
{
alert("事件类型：" + event.type);
}
document.write("单击...");
document.onmousedown = getEvent; //这里没有括号，不可以写成 getEvent(event);
</script>
</body>
</html>
再看一个：
<!DOCTYPE html>
<html>
<head>
<title>js17.html</title>
</head>
<body>
<input type="button" id="button1" value = "button1 ">
<script type="text/javascript">
var v = document.getElementById("button1");
v.onclick = function clickHandler()
{
alert ("button is clicked.");
}
</script>
</body>
</html>
安安