以下代码用于在用户按空格键时在屏幕上移动一个小红色div。在“拍摄”功能中,我创建一个新的div并设置超时,然后它将从'moveLazer'功能开始向上移动屏幕。
问题:如果您拍摄几次,当一个div击中屏幕顶部时,“lazerLifeCycle”变量会清除,但也会清除仍在移动但尚未移动到顶部的第二个或第三个div的超时。从我看到,使用setInterval并不能解决问题。我知道它因为lazerLifeCycle是全局的,但我没有看到正确的方法。请帮忙! js和html如下。请注意,如果要复制/粘贴并尝试,它们是2个不同的文件。在firefox或chrome中运行它。它在IE中没有任何作用。
//level3.js
var lazerId = 1;
var init = function(){
var ship = document.getElementById('randRect');
ship.style.left = '700px';
ship.style.top = '300px';
}
document.onkeyup = function(e) {
if(e.keyCode == 37) {
moveLeft();
} else if(e.keyCode == 39){
moveRight();
} else if(e.keyCode == 32){
shoot();
}
}
var shoot = function(){
lazerId = lazerId + 1;
var ship = document.getElementById('randRect');
width = parseInt(ship.clientWidth);
xPos = parseInt(ship.style.left);
middle = ((xPos + (width/2)) - 3) + 'px'; //-3 is to center it i think
var lazer = document.createElement('div');
lazer.id = lazerId;
var body = document.getElementById('body');
body.appendChild(lazer);
lazer.style.position = 'absolute';
lazer.style.width = '7px';
lazer.style.height = '13px';
lazer.style.left = middle;
lazer.style.top = '287px';
lazer.style.backgroundColor = 'red';
lazerLifeCycle = setTimeout('moveLazer(' + lazerId.toString() + ');', 10);
}
var moveLazer = function(lazerElementId){
var lazer = document.getElementById(lazerElementId.toString());
var lazerTop = parseInt(lazer.style.top);
if( (lazerTop - 1) < 0){
lazer.style.top = '0px';
clearTimeout(lazerLifeCycle);
} else {
lazer.style.top = (lazerTop - 1) +'px'
lazerLifeCycle = setTimeout('moveLazer(' + lazerElementId.toString() + ');', 10);
}
}
var moveLeft = function(){
var ship = document.getElementById('randRect');
shipXPos = parseInt(ship.style.left);
if( (shipXPos - 15) < 0){
ship.style.left = 0+'px';
} else {
ship.style.left = shipXPos - 15+'px';
}
}
var moveRight = function(){
var ship = document.getElementById('randRect');
shipXPos = parseInt(ship.style.left);
if( (shipXPos + 15) > 1300){
ship.style.left = 1300+'px';
} else {
ship.style.left = shipXPos + 15+'px';
}
}
window.onload = init;
//level3.html
<html>
<head>
<title>random</title>
<style type="text/css">
.random{
position:absolute;
background: orange;
padding: 7px;
}
</style>
<script src="level3.js" type="text/javascript">
</script>
</head>
<body id="body">
<div id="randRect" class="random"><center><-- or --><center></div>
</body>
</html>
答案 0 :(得分:0)
<强> Working Demo 强>
好的是一个简化的vs改变了代码。
var shoot = function(){
lazerLifeCycle = moveLazer(lazerId);
}
var moveLazer = function(lazerElementId){
var lazer = document.getElementById(lazerElementId.toString());
var lazerTop = parseInt(lazer.style.top);
if( (lazerTop - 1) < 0){
lazer.style.top = '0px';
} else {
lazer.style.top = (lazerTop - 1) +'px'
setTimeout(function(){moveLazer(lazerElementId);}, 10);
}
}
基本上你不需要担心清除超时,因为除非你告诉他们,否则他们不会再次发生。此外,为了使您能够拍摄多个激光器,您只需要引用传递给moveLazer
的ID即可。基本上它会继续,直到激光击中顶部。还允许支持多次拍摄。