div通过键盘事件上下左右实现div块的移动
效果：
实现：
js：
var Method=(function () { return { EVENT_ID:"event_id", loadImage:function (arr) { var img=new Image(); img.arr=arr; img.list=[]; img.num=0; // 如果DOM对象下的事件侦听没有被删除掉，将会常驻堆中 // 一旦触发了这个事件需要的条件，就会继续执行事件函数 img.addEventListener("load",this.loadHandler); img.self=this; img.src=arr[img.num]; }, loadHandler:function (e) { this.list.push(this.cloneNode(false)); this.num++; if(this.num>this.arr.length-1){ this.removeEventListener("load",this.self.loadHandler); var evt=new Event(Method.EVENT_ID); evt.list=this.list; document.dispatchEvent(evt); return; } this.src=this.arr[this.num]; }, $c:function (type,parent,style) { var elem=document.createElement(type); if(parent) parent.appendChild(elem); for(var key in style){ elem.style[key]=style[key]; } return elem; }, divColor: function () { var col="#";//这个字符串第一位为# 颜色的格式 for(var i=0;i<6;i++){ col+=parseInt(Math.random()*16).toString(16);//rondom*16后的随机值即为0-1*16==0-16; toString(16)为转化为16进制 } return col;//最后返回一个七位的值 格式即为#nnnnnn 颜色的格式 }, random:function (min,max) { max=Math.max(min,max); min=Math.min(min,max); return Math.floor(Math.random()*(max-min)+min); }, dragElem:function (elem) { elem.addEventListener("mousedown",this.mouseDragHandler); elem.self=this; }, removeDrag:function (elem) { elem.removeEventListener("mousedown",this.mouseDragHandler); }, mouseDragHandler:function (e) { if(e.type==="mousedown"){ e.stopPropagation(); e.preventDefault(); document.point={x:e.offsetX,y:e.offsetY}; document.elem=this; this.addEventListener("mouseup",this.self.mouseDragHandler); document.addEventListener("mousemove",this.self.mouseDragHandler); }else if(e.type==="mousemove"){ this.elem.style.left=e.x-this.point.x+"px"; this.elem.style.top=e.y-this.point.y+"px"; }else if(e.type==="mouseup"){ this.removeEventListener("mouseup",this.self.mouseDragHandler); document.removeEventListener("mousemove",this.self.mouseDragHandler); } } } })();
html：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <script src="https://www.jb51.net/js/Method.js"></script> </head> <body> <script> var div; var code=[]; var speed=2; var bool=false; init(); function init() { div=Method.$c("div",document.body,{ width:"50px", height:"50px", backgroundColor:"red", position:"absolute", left:0, top:0 }); window.addEventListener("keydown",keyHandler); window.addEventListener("keyup",keyHandler); setInterval(animation,16); } function keyHandler(e) { if(e.type==="keydown" && (!bool || code.indexOf(e.keyCode)===-1)){ bool=true; code.push(e.keyCode); }else if(e.type==="keyup"){ bool=false; code.length=0; } } function animation() { if(!bool)return; for(var i=0;i<code.length;i++){ switch (code[i]){ case 37: div.style.left=div.offsetLeft-speed+"px"; break; case 38: div.style.top=div.offsetTop-speed+"px"; break; case 39: div.style.left=div.offsetLeft+speed+"px"; break; case 40: div.style.top=div.offsetTop+speed+"px"; break; } } } </script> </body> </html>