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js初识第十二节

js初识第十二节

作者: An的杂货铺 | 来源:发表于2019-08-22 10:55 被阅读0次

    div移动和发射子弹的案例

    <!DOCTYPE html>
    
    <html>
    
    <head>
    
    <meta charset="utf-8" />
    
    <title>键盘事件和组合键</title>
    
    <style>
    
    *{
    
    margin: 0;
    
    padding: 0;
    
    }
    
    #div1{width:40px;
    
    height:40px;
    
    position:absolute;
    
    background:orange;
    
    transform:rotate(0deg);
    
    }
    
    .pd{
    
    width:5px;
    
    height:15px;
    
    border-radius:50%;
    
    position:absolute;
    
    background:#f06;
    
    }
    
    </style>
    
    </head>
    
    <body>
    
    <div id="div1" style="top:350px;left:100px"></div>
    
    </body>
    
    </html>
    
    <script>
    
    var div1 = document.getElementById("div1");
    
    document.onkeydown = function(e) {
    
    var e = e || window.event;
    
    var code = e.keyCode || e.which;
    
    //alert(code);
    
    switch (code) {
    
    case 37:
    
          // 按的是<-
    
    
    
          div1.style.left = (div1.offsetLeft - 10<0?0:div1.offsetLeft - 10)+'px';
    
          //考虑边界条件
    
          break;
    
        case 39:
    
          // 按的是->
    
          //考虑边界条件
    
          if (div1.offsetLeft+div1.offsetWidth>=document.body.clientWidth) {
    
            div1.offsetLeft = document.body.clientWidth - div1.offsetWidth;
    
            div1.style.left = div1.offsetLeft + 'px';
    
          }else{
    
          div1.style.left = div1.offsetLeft + 10 +'px';
    
          }
    
          break;
    
    case 32:
    
        // 按的是空格 创建子弹    
    
    var bullet = document.createElement("div");
    
    document.body.appendChild(bullet);
    
    bullet.className = "pd";
    
    bullet.style.left = div1.offsetLeft + div1.offsetWidth/2 - bullet.offsetWidth/2 + "px";
    
    bullet.style.top = div1.offsetTop - bullet.offsetHeight + "px";
    
    var tt = 0;
    
    setInterval(function(){
    
                        if (parseInt(bullet.style.top)<-20) {
    
                        bullet.remove();
    
                        }else{
    
                        bullet.style.top = div1.offsetTop - bullet.offsetHeight - tt + 'px';
    
                        }
    
                        tt+=50;
    
    },100);
    
    }
    
    }
    
    </script>
    

    固定导航栏的案例

    <!DOCTYPE html>
    
    <html>
    
    <head lang="en">
    
        <meta charset="UTF-8">
    
        <title></title>
    
        <style>
    
            *{
    
            margin:0;
    
            padding:0;
    
            }
    
    #one{
    
    width:100%;
    
    height:80px;
    
    background: pink;
    
    }
    
    #two{
    
    width:100%;
    
    height:40px;
    
    line-height: 40px;
    
    text-align:center;
    
    background:green;
    
    }
    
    #three{
    
    width:100%;
    
    height:2000px;
    
    background:orange;
    
    }
    
    .divFixed{
    
    position:fixed;
    
    top:0;
    
    }
    
        </style>
    
    </head>
    
    <body>
    
    <div id="one"></div>
    
    <div id="two">这里以后是导航栏</div>
    
    <div id="three"></div>
    
    </body>
    
    </html>
    
    <script type="text/javascript">
    
        function $(id) {
    
    return document.getElementById(id);
    
    }
    
    window.onscroll = function(){
    
    var top = document.body.scrollTop || document.documentElement.scrollTop;
    
    if(top>80){
    
              $('two').classList.add('divFixed');
    
    }else{
    
    $('two').className = '';
    
    }
    
    }
    
    </script>
    

    放大镜案例

    <!DOCTYPE html>
    
    <html>
    
    <head>
    
    <meta charset="UTF-8">
    
    <title></title>
    
    </head>
    
    <style type="text/css">
    
    *{
    
    margin: 0;
    
    padding: 0;
    
    }
    
    #box{
    
    width: 350px;
    
    height: 350px;
    
    border: 1px solid #000;
    
    margin: 200px;
    
    position: relative;
    
    }
    
    #big{
    
    width: 400px;
    
    height: 400px;
    
    border: 1px solid #000;
    
    overflow: hidden;
    
    position: absolute;
    
    top:0;
    
    left : 360px;
    
    display: none;
    
    }
    
    #mask{
    
    width: 175px;
    
    height: 175px;
    
    background: paleturquoise;
    
    position: absolute;
    
    left:0;
    
    top: 0;
    
    opacity: 0.3;
    
    display: none;
    
    cursor: move;
    
    }
    
    #small{
    
    position: relative;
    
    }
    
    #bigImg{
    
    position: absolute;
    
    left: 0;
    
    top: 0;
    
    }
    
    </style>
    
    <body>
    
    <div id="box" >
    
    <div id="small"><!--小图区-->
    
    <img src="001.jpg" alt="" />
    
    <div id="mask"></div><!--遮罩层-->
    
    </div>
    
    <div id="big"><!--大图区-->
    
    <img src="0001.jpg" alt="" id="bigImg"/>
    
    </div>
    
    </div>
    
    </body>
    
    </html>
    
    <script type="text/javascript">
    
    function $(id) {
    
    return document.getElementById(id);
    
    }
    
        var box = $('box');
    
        var small = $('small');
    
        var mask = $('mask');
    
        var big = $('big');
    
        var bigImg = $('bigImg');
    
        //鼠标滑进小图区时显示大图区,显示小图区域遮罩
    
        small.onmouseover = function(e){
    
        var e = e||event;
    
        big.style.display = 'block';
    
        mask.style.display = 'block';
    
        }
    
        small.onmouseout = function(e){
    
        var e = event;
    
        big.style.display = 'none';
    
        mask.style.display = 'none';
    
        }
    
        small.onmousemove = function(e){
    
            var e = e||event;
    
            var x = e.pageX - box.offsetLeft-mask.offsetWidth/2;
    
            console.log(x);
    
            var y = e.pageY - box.offsetTop-mask.offsetHeight/2;
    
            // var maxX = box.clientWidth-mask.clientWidth;
    
            // var maxY = box.clientHeight-mask.clientHeight;
    
            //以上写法也可行
    
            console.log(y);
    
            var maxX = box.offsetWidth-mask.offsetWidth;
    
            var maxY = box.offsetHeight-mask.offsetHeight;
    
            x = x<0?0:(x>maxX?maxX:x)
    
            y = y<0?0:(y>maxY?maxY:y)
    
            mask.style.left = x+'px';
    
            mask.style.top = y+'px';
    
            //放大大图里面的图片
    
            // 小图片宽度:大图片宽度 = x: 大图片位置
    
            var BX = x*bigImg.clientWidth/small.clientWidth;
    
            var BY = y*bigImg.clientHeight/small.clientHeight;
    
            bigImg.style.left = -BX+'px';
    
            bigImg.style.top = -BY+'px';
    
        }
    
    </script>
    

    一个无缝滚动的案例

    <!DOCTYPE html>
    
    <html>
    
    <head>
    
    <meta charset="UTF-8">
    
    <title></title>
    
    </head>
    
    <style>
    
    *{
    
    margin:0;
    
    padding:0;
    
    }
    
    div{
    
    width:600px;
    
    height:200px;
    
    position:relative;
    
    border:1px solid red;
    
    margin:100px;
    
    overflow:hidden;
    
    }
    
    ul{
    
    width:600%;
    
    position:absolute;
    
    left:0;
    
    }
    
    li{
    
    float:left;
    
    list-style:none;
    
    }
    
    </style>
    
    <body>
    
    <div id="box">
    
    <ul id="u">
    
    <li><img src="a.jpg" alt="" /></li>
    
    <li><img src="b.jpg" alt="" /></li>
    
    <li><img src="c.jpg" alt="" /></li>
    
    <li><img src="d.jpg" alt="" /></li>
    
    <!-- 重复放两张图片是为了让无缝滚动看起来没有间隔 -->
    
    <li><img src="a.jpg" alt="" /></li>
    
    <li><img src="b.jpg" alt="" /></li>
    
    </ul>
    
    </div>
    
    </body>
    
    </html>
    
    <script>
    
    //一个无缝滚动的轮播案例
    
    var oul = document.getElementById('u');
    
    var dis = 0;
    
    var timer = setInterval(auto,100);
    
    function auto(){
    
    oul.style.left = dis+'px';
    
            dis-=20;
    
            if(parseInt(oul.style.left)<=-1200){
    
            dis = 0;
    
            }
    
    }//单独抽离出来当做一个函数处理是为了鼠标移出区域的时候方便重新调用
    
        oul.onmouseover = function(){
    
        clearInterval(timer);
    
        }
    
        oul.onmouseout = function(){
    
          timer = setInterval(auto,100);
    
        }
    
    //    var oul = document.getElementById('u');
    
    // var dis = 0;
    
    // function autoplay(){
    
    // oul.style.left = dis+'px';
    
    // dis-=10;
    
    // if(dis<=-1200){
    
    // dis = 0;
    
    // }
    
    // }
    
    // var timer = setInterval(autoplay,100);
    
    // oul.onmouseover = function(){
    
    // clearInterval(timer);
    
    // }
    
    // oul.onmouseout = function(){
    
    //        timer = setInterval(autoplay,100)
    
    // }
    
    </script>
    
    
    

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