本文实例讲述了JS控制层作圆周运动的方法。分享给大家供大家参考,具体如下:
<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\"
\"http://www.w3.org/TR/html4/strict.dtd\">
<html>
<head>
<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">
<title>圆周运动</title>
<script type = \"text/javascript\">
window.onload = function(){
var ctrlBtn = $id(\"ctrl\");
var isMove = true;
oM = null;
ctrlBtn.onclick = function(){
if(isMove){
moveByCircle();
}else{
clearInterval(oM);
}
isMove = !isMove;
}
}
function moveByCircle(){
var bacL = parseInt($id(\"clockBac\").style.left);
var bacT = parseInt($id(\"clockBac\").style.top);
var bacW = parseInt($id(\"clockBac\").style.width);
var bacH = parseInt($id(\"clockBac\").style.height);
var initL = bacL+bacW/2;
var initT = bacT+bacH/2;
var step = 0;
var r = 65;
$id(\"tt\").style.left = initL+\"px\";
$id(\"tt\").style.top = initT+\"px\";
var l = parseInt($id(\"tt\").style.left);
var t = parseInt($id(\"tt\").style.top);
oM = window.setInterval(function(){
if (step == 360) {
step = 1;
}
$id(\"tt\").style.left = (l + r * Math.sin(step)) + \"px\";
$id(\"tt\").style.top = (t - r * Math.cos(step)) + \"px\";
step += 3.14/30;
var d = new Date();
var hh = d.getHours();
var mm = d.getMinutes();
var ss = d.getSeconds();
$id(\"ctrl\").value = hh+\":\"+mm+\":\"+ss;
}, 1000);
}
function $id(id){
return document.getElementById(id);
}
</script>
</head>
<body>
<div id = \"tt\" style =\"width:10px;height:10px;background:red;position:absolute;top:105px;left:130px;\"></div>
<input type = \"button\" id = \"ctrl\" style = \"width:100px;position:absolute;\"/>
<img src = \"../img/clock.jpg\" id = \"clockBac\" style =\"width:200px;height:200px;top:100px;left:100px;position:absolute;z-index:-999\"/>
</body>
</html>
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希望本文所述对大家JavaScript程序设计有所帮助。
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