JavaScript实现的使用键盘控制人物走动实例

时间:2022-01-27 12:28:09

其实这个示例用到了js的两个核心时间,键盘事件onkeydown,周期执行事件setInterval。

实现效果

当按下键盘某个键时网页中的人物实现相应的动作,达到利用键盘控制走动效果

实现步骤

一、预订键值作用:

w:向上
s:向下
a:向左
d:向右
空格:停止

二、预订键值后,要能捕获按键事件以及判断用户按的是哪个键?

捕获键盘事件可以用onkeydown
获取键值码可以用event.keyCode
 
三、用setInterval周期执行事件替换图片

替换图片是为了实现任务走动效果
但要注意使用clearInterval清除周期执行,否则会越走越快

示例代码:

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<html>
    <head>
        <meta charset="utf-8" />
        <title>人物走动</title>
    </head>
    <body onkeydown="show()">
        <ul style="posttion:absolute;border:1px solid #999;list-style:none;width:150px;padding:20px;background:#ffffef;">
            <li>w:向上</li>
            <li>s:向下</li>
            <li>a:向左</li>
            <li>d:向右</li>
            <li>空格:停止</li>
            <li style="margin-top:20px;"><u><a href="http://www.zzvips.com">服务器之家</a></u></li>
        </ul>
        <div style="position:absolute;top:0;left:0" id='di'><img src="//img.jbzj.com/file_images/article/201408/201482791327688.gif?201472791345" id="img"></div>
        <script>
            var img1='//img.jbzj.com/file_images/article/201408/201482791656841.gif?201472791722';
            var img2='//img.jbzj.com/file_images/article/201408/201482791327688.gif?201472791345';
            var x=0;
            var y=0;
            var xs=0;
            var ys=0;
            var flag=true;
            var zq=null;
            function ks(){
                zq=setInterval(function(){ 
                    var s=document.getElementById('img');  
                    var str=s.src;
                    var area=document.getElementById('di');
                    var xpos=parseInt(area.style.left);
                    var ypos=parseInt(area.style.top);
                    x=x+xs;
                    y=y+ys;
                    area.style.left=x;
                    area.style.top=y;
                    var pos=str.lastIndexOf('/')+1;
                    var hz=str.substr(pos);
                    if(hz==img1){
                        s.src= img2;
                    }else{
                        s.src= img1;
                    }              
                },50);
            }
            ks();
 
            function show(){
                var sz=window.event.keyCode;
                switch(sz){
                    case 87:
                        img1='//img.jbzj.com/file_images/article/201408/ren_h_1.gif';
                        img2='//img.jbzj.com/file_images/article/201408/ren_h_2.gif';
                        ys=-5;
                        xs=0;
                        break;
                    case 65:
                        img1='//img.jbzj.com/file_images/article/201408/ren_l_1.gif';
                        img2='//img.jbzj.com/file_images/article/201408/ren_l_2.gif';
                        xs=-5;
                        ys=0;
                        break;
                    case 68:
                        img1='//img.jbzj.com/file_images/article/201408/ren_r_1.gif';
                        img2='//img.jbzj.com/file_images/article/201408/ren_r_2.gif';
                        xs=5;
                        ys=0;
                        break;
                    case 83:
                        img1='//img.jbzj.com/file_images/article/201408/ren_q_1.gif';
                        img2='//img.jbzj.com/file_images/article/201408/ren_q_2.gif';
                        ys=5;
                        xs=0;
                        break;
                    case 32:
                      if(flag){
                          clearInterval(zq);
                          flag=false;
                          break;
                       }
                    case 13:
                     if(!flag){
                         ks();
                         flag=true;
                        break;
                      }
                }
            }
        </script>
    </body>
</html>