<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="js/jquery.min.js"></script>
<style>
body{
position: relative;
margin:0;
padding:0;
width:100%;
height: 1000px;
}
#box{
height: 50px;
width:200px;
position: absolute;
left:50%;
top:50%;
margin-left:-200px;
margin-top:-200px;
background: #CDCDCD;
}
#small-box{
height: 50px;
width:50px;
position: absolute;
left:0;
top:0;
background: #FF66CC;
cursor:move ;
opacity: 0.7;
}
</style>
</head>
<body>
<div id="box">
<div id="small-box"></div>
</div>
<script>
var box=$("#small-box");
var body=$('body');
var index=0;
var x1;
box.mousedown(function(){
index=1; //鼠标按下才能触发onmousemove方法
var x=event.clientX; //鼠标点击的坐标值，x
var left= this.style.left;
left=left.substr(0,left.length-2); //去掉px
x1=parseInt(x-left);
});
box.mousemove(function(){
if(index===1){
this.style.left=event.clientX-x1+'px';
if(this.style.left.substr(0,this.style.left.length-2)<0){
this.style.left=0;
};
if(this.style.left.substr(0,this.style.left.length-2)>150){
this.style.left='150px';
};
}
});
box.mouseup(function(){
index=0;
});
body.mouseup(function(){
index=0;
});
</script>
</body>
</html>
来源：CSDN
作者：LLLiiv
链接：https://blog.csdn.net/llllvvv/article/details/79928707