原生：点击创建div，且能够拖动
css、html
<style type="text/css">
.active{
100px;
height: 100px;
position: absolute;
}
</style>
<body>
<input type="button" value="创建div" id="oBtn" />
</body>
js
<script src="public.js"></script>
<script>
var btn = document.getElementById("oBtn");
btn.onclick = function(){
new DragDiv().init()
}
function DragDiv(){
this.div = document.createElement("div");
this.init = function(){
document.body.appendChild(this.div);
this.div.className = "active";
this.div.style.left = rand(0,window.innerWidth - 100) + "px";
this.div.style.top = rand(0,window.innerHeight - 100) + "px";
this.div.style.background = getColor();
this.drag();
}
this.drag = function(){
//这里的this还是实例
this.div.onmousedown = function(e){
e = e || event;
this.down(e);
document.onmousemove = function(e){
e = e || event;
this.move(e);
}.bind(this)
document.onmouseup = function(){
this.up();
}.bind(this);
return false;
}.bind(this)
}
this.down = function(e){
this.disX = e.offsetX;
this.disY = e.offsetY;
}
this.move= function(e){
this.div.style.left = e.pageX - this.disX + "px";
this.div.style.top = e.pageY - this.disY + "px";
}
this.up = function(){
document.onmousemove = null;
}
}
</script>
public.js
function $id(id){//给我一个id名，返回一个这个id的元素
return document.getElementById(id);
}
//求随机数
function rand(min,max){
return Math.round(Math.random()*(max - min) + min);
}
//随机的16进制颜色
function getColor(){
var str = "0123456789ABCDEF";//十六进制字符串
var color = "#";
for(var i = 0; i <= 5; i++){//取6个数
color += str.charAt(rand(0,15));
//rand(0,15)随机0-15之间的数，作为charAt()的下标，取出下标对应的字符
}
return color;
}
function zero(val){
return val < 10 ? "0" + val : val;
}
//时间差
function diff(start,end){//2000-2018 2018 - 2000
//console.log(start.getTime());
return Math.abs(start.getTime() - end.getTime())/1000;
}