示例代码：
HTML文件：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>HTML文件</title>
<script>
window.onload=function () {
var d=document.getElementById('d');
//内容发生改变，并焦点发生改变，才可以监听到
d.onchange=function () {
alert('内容发生改变')
}
}
</script>
</head>
<body>
<input type="text" id="d" value="">
</body>
</html>
键盘事件：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>键盘事件</title>
<script>
window.onload=function () {
window.onkeypress=function (e) {
// alert(e.key)//弹出按键对应的字母
// alert(e.keyCode)
if (e.charCode==103){
alert('G键被点击')
}
}
}
</script>
</head>
<body>
</body>
</html>
鼠标事件：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>鼠标事件</title>
<script>
window.onload=function () {
var input=document.getElementById('b');
input.onclick=function () {
alert('按钮被点击了');
}
var c= document.getElementById('c');
c.ondblclick=function () {
alert('双击')
}
}
</script>
</head>
<body>
<input type="button" id="b" value="点击">
<input type="button" id="c" value="双击">
</body>
</html>