案例：碰撞检测
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
.box {
position: absolute;
left: 0;
top: 0;
width: 100px;
height: 100px;
background: red;
}
.box2 {
position: fixed;
left: calc(50% - 50px);
top: calc(50% - 50px);
width: 100px;
height: 100px;
background: green;
}
</style>
</head>
<body>
<div class="box">文字</div>
<div class="box2"></div>
<script src="fns.js"></script>
<script>
{
// 拖拽
let box = document.querySelector(".box");
let box2 = document.querySelector(".box2");
// 鼠标按下事件
let startMouse = {};
let startEl = {};
// 鼠标移动
let move = (e)=>{
let nowMouse = {
x: e.clientX,
y: e.clientY
};
let disMouse = {
x: nowMouse.x - startMouse.x,
y: nowMouse.y - startMouse.y
};
css(box,"left",startEl.x + disMouse.x);
css(box,"top",startEl.y + disMouse.y);
if(boom(box,box2)){
box2.style.background = "yellow";
} else {
box2.style.background = "green";
}
};
box.addEventListener("mousedown",(e)=>{
startMouse = {
x: e.clientX,
y: e.clientY
};
startEl = {
x: css(box,"left"),
y: css(box,"top")
}
document.addEventListener("mousemove",move);
document.addEventListener("mouseup",()=>{
document.removeEventListener("mousemove",move);
},{
once: true
});
e.preventDefault();
});
}
function boom(el,el2){
let rectEl1 = el.getBoundingClientRect();
let rectEl2 = el2.getBoundingClientRect();
if(rectEl1.right < rectEl2.left
|| rectEl2.right < rectEl1.left
|| rectEl1.bottom < rectEl2.top
|| rectEl2.bottom < rectEl1.top){
return false;
}
return true;
}
</script>
</body>
</html>
