<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>键盘事件小练习</title>
<style>
#mydiv{
width: 30px;
height: 30px;
background-color: red;
position: absolute;
left: 0;
top: 0;
}
</style>
</head>
<body>
<div id="mydiv"></div>
<script>
var myDiv = document.getElementById("mydiv");
var xs = 0;
var xv = 30;
var ys = 0;
var yv = 30;
document.onkeydown = function(event){
var kc = event.keyCode;
switch (kc){
case 37:
xs -= xv;
myDiv.style.left = xs+"px";
myDiv.style.backgroundColor = "red";
break;
case 38:
ys -= yv;
myDiv.style.top = ys + "px";
myDiv.style.backgroundColor = "blue";
break;
case 39:
xs+=xv;
myDiv.style.left = xs+"px";
myDiv.style.backgroundColor = "green";
break;
case 40:
ys += yv;
myDiv.style.top = ys + "px";
myDiv.style.backgroundColor = "yellow";
break;
}
}
</script>
</body>
</html>