• js的一些实用小案例


    1、轮播图(思路见代码)

      实现效果:点击下方的按钮,实现相应的图片的切换,点击左右按钮,实现向左或者向右切换图片,轮播图自动轮播,当鼠标移到图片上方,自动轮播停止,鼠标移除后,自动轮播恢复

      实现思路: 对标签的class属性的属性值进行操作,先写好对应的属性值的样式及效果,然后利用js对属性值进行操作

    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>Document</title>
        <style>
            .container{
                width: 360px;
                height: 277px;
                border: 10px solid #000;
                overflow: hidden;
                margin: 0 auto;
                position: relative;
            }
            .btns{
                position: absolute;
                bottom: 20px;
                width: 100%;
                height: 20px;
                background: #fff;
                z-index: 999;
            }
            .btns button{
                border-radius: 50%;
            }
            .content{
                height: 257px;
                text-align: center;
                line-height: 257px;
                font-size: 100px;
                position: relative;
            }
            .box{
                width: 100%;
                height: 100%;
                position: absolute;
                background: #000;
                color: #fff;
                opacity: 0;
                /* transform: rotate(0deg); */
                transition: opacity 1s,transform 1s;
            }
            .box img{
                width: 100%;
                height: 100%;
            }
            button.active{
                color: aliceblue;
                background: black;
            }
            .box.active{
                display: block;
                z-index: 1;
                opacity: 1;
                /* transform: rotate(360deg); */
            }
            #left_btn,#right_btn{
                position: absolute;
                top: 50%;
                margin-top: -10px;
                z-index: 999;
            }
            #right_btn{
                right: 0;
            }
        </style>
    </head>
    <body>
        <div class="container">
            <div class="btns">
                <button data-index="0" class="btn active">1</button>
                <button data-index="1" class="btn">2</button>
                <button data-index="2" class="btn">3</button>
            </div>
            <div class="content">
                <div class="box active"><img src="https://img20.360buyimg.com/da/s1180x940_jfs/t1/22886/39/6392/67839/5c53100aEeaae8352/7a4d3de1156321ae.jpg.webp" alt=""></div>
                <div class="box"><img src="https://img11.360buyimg.com/pop/s1180x940_jfs/t1/94077/40/13431/91413/5e57629eE39ab060a/4adceb3e5e3863fe.jpg.webp" alt=""></div>
                <div class="box"><img src="https://img20.360buyimg.com/pop/s1180x940_jfs/t1/95963/25/13739/84993/5e606cc3Eaf064df7/edd18ca669882399.jpg.webp" alt=""></div>
            </div>
            <button id="left_btn">left</button>
            <button id="right_btn">right</button>
        </div>
        <script>
            var ele_btns = document.querySelectorAll(".btn");
    
            var ele_boxs = document.querySelectorAll(".box");
            var ele_left = document.getElementById("left_btn");
            var ele_right = document.getElementById("right_btn");
            var ele_container = document.querySelector(".container")
            var index = null;
    
            //轮播图下方按钮
            for(var i = 0; i < ele_btns.length; i++){
                ele_btns[i].addEventListener("click" , function(){
                    //调用下方函数移除所有的active属性
                    removeClass(ele_btns , "active");
                    removeClass(ele_boxs , "active");
                    for(var j = 0; j < ele_btns.length; j++){
                        //确定点击的按钮对应的图片
                        if(this === ele_btns[j]){
                            break;
                        }
                    }
                    //将对应的图片的下标赋值给全局变量,(对应下标即获取的ele_boxs中的下标)
                    index = j;
                    //给当前点击的按钮添加active属性
                    this.className += " active";
                    //给当前对应的按钮的图片添加active属性
                    ele_boxs[index].className += " active";
                })
            }
            
            //左边按钮
            ele_left.addEventListener("click" , function(){
                //调用下方函数移除所有的active属性
                removeClass(ele_btns , "active");
                removeClass(ele_boxs , "active")
                //向左切换,即下标递减
                index--;
                //当下标小于0时从左后面的图片重新开始
                if(index < 0){
                    index = ele_btns.length -1;
                }
                //对应的按钮及图片添加active
                ele_btns[index].className += " active";
                ele_boxs[index].className += " active"
            })
    
            ele_right.addEventListener("click" , function(){
                removeClass(ele_btns , "active");
                removeClass(ele_boxs , "active")
                index++;
                if(index > ele_btns.length - 1){
                    index = 0;
                }
                ele_btns[index].className += " active";
                ele_boxs[index].className += " active"
            })
    
            //定时自动轮播图片
            var timer = null;
            timer = setInterval(function(){
                removeClass(ele_btns , "active");
                removeClass(ele_boxs , "active")
                index++;
                if(index > ele_btns.length - 1){
                    index = 0;
                }
                ele_btns[index].className += " active";
                ele_boxs[index].className += " active"
            } , 1000)
    
            //当鼠标移到图片上方时,停止自动轮播
            ele_container.addEventListener("mouseover", function(){
                clearInterval(timer);
            })
    
            //当鼠标从图片上方移走时,开启自动轮播
            ele_container.addEventListener("mouseout", function(){
                    timer = setInterval(function(){
                    removeClass(ele_btns , "active");
                    removeClass(ele_boxs , "active")
                    index++;
                    if(index > ele_btns.length - 1){
                        index = 0;
                    }
                    ele_btns[index].className += " active";
                    ele_boxs[index].className += " active"
                } , 1000)
            })
    
            //清除所有的active属性
            function removeClass(ele , class_name){
                for(var i = 0; i <ele.length ; i++){
                    //将所有的属性名切割成数组
                    ele_class_arr = ele[i].className.split(" ");
                    //如果数组中存在想要删除的属性(即上方的active属性),就进入if中
                    if(ele_class_arr.indexOf(class_name) !== -1){
                        //删除掉active属性
                        ele_class_arr.splice(ele_class_arr.indexOf(class_name) , 1);
                    }
                    //将删除掉active属性的数组重新转换成字符串
                    ele_class_str = ele_class_arr.join(" ");
                    //将转换完成之后的字符串赋予给对应的DOM的属性中
                    ele[i].className = ele_class_str;
                }
            }
         
         
        </script>
    </body>
    </html>
    View Code

    2、鼠标拖拽回放

      实现效果:鼠标左键在box上方按下,保持鼠标左键按下拖拽鼠标,box会跟随鼠标一起移动,鼠标左键抬起,box停止跟随,点击回放按钮,box会按照原路径进行返回

      实现思路:拖拽 :将鼠标的位置赋值给按照一定的规律赋值给box的偏移量,回放:将鼠标的移动坐标添加到一个对象中,点击回放,倒序将坐标赋值给box偏移量

    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>Document</title>
        <style>
            #box{
                width: 100px;
                height: 100px;
                background: yellowgreen;
                position: absolute;
                left: 0;
                top: 0;
            }
        </style>
    </head>
    <body>
        <div id="box">
            <button id="replay">回放</button>
        </div>
        <script>
            var ele_box = document.getElementById("box");
            var ele_replay = document.getElementById("replay")
            //开启鼠标拖拽判断
            var flag = false;
    
            //鼠标按下时到box的距离
            var offset_X = null;
            var offset_Y = null;
            //拖拽边界
            var right_boundary = null;
            var bottom_boundary = null;
    
            var position_list = [];
            
            //鼠标按下
            ele_box.addEventListener("mousedown" , function( evt ){
                flag = true;
                var e = evt || event;
                //获取鼠标按下时距离box的边框的距离
                offset_X = e.offsetX;
                offset_Y = e.offsetY;
                //右边界与下边界
                right_boundary = document.body.offsetWidth - ele_box.offsetWidth;
                bottom_boundary = document.documentElement.clientHeight - ele_box.offsetHeight;  
                
                //记录鼠标按下时box的位置
                position_list.push({
                    x : ele_box.offsetLeft,
                    y : ele_box.offsetTop
                })
                console.log(position_list)
            })
            //鼠标移动时
            document.addEventListener("mousemove" , function( evt ){
                var e = evt || event;
                if(flag === false){
                    return false
                }
                //让鼠标的光标处在鼠标点击的位置
                var left = e.clientX - offset_X;
                var top = e.clientY - offset_Y;
    
                //判断时候到了边界
                top = top <= 0 ? 0 : top;
                top = top >= bottom_boundary ? bottom_boundary : top;
                left = left <= 0 ? 0 :left;
                left = left >= right_boundary ? right_boundary : left;
    
                ele_box.style.left = left + "px";
                ele_box.style.top = top + "px";
                //在位置对象position_list中获取鼠标上一次移动的位置
                var last_item = position_list[position_list.length - 1];
                //只记录每次移动超过5px的位置
                if(Math.abs(left - last_item.x) > 5 || Math.abs(top - last_item.y)){
                    position_list.push({
                        x : left,
                        y : top
                    })
                }
            })
            //鼠标抬起时,改变状态,关闭鼠标拖拽
            ele_box.addEventListener("mouseup",function( evt ){
                flag = false
            })
    
            var timer = null;
            //回放功能,倒叙读取位置对象position_list中的每一个坐标
            ele_replay.addEventListener("click",function(){
                clearInterval(timer)
                timer = setInterval(function(){
                    // 删除数组之中最后一项,每个被删除的项都要单独使用一下;
                    var item = position_list.pop();
                    ele_box.style.left = item.x + "px";
                    ele_box.style.top  = item.y + "px";
                    if(position_list.length === 0){
                            clearInterval(timer);
                        }
                 },20)
            })
           
        </script>
    </body>
    </html>
    View Code

    3、鼠标跟随提示框

    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>Document</title>
        <style>
            .tip-box{
                position: absolute;
                left: 0;
                top: 0;
                width: 200px;
                height: 100px;
                background: #ddd;
                border: #b6b6b6;
                display: none;
            }
            li{
                margin: 20px;
            }
        </style>
    </head>
    <body>
        <div class="container">
            <ol class="title-list">
                <li>
                    <a href="" title="4399小游戏">4399小游戏</a>  
                    <div class="tip-box">
                        4399小游戏4399小游戏4399小游戏4399小游戏4399小游戏4399小游戏4399小游戏4399小游戏
                    </div>
                </li>
                <li>
                    <a href="">7k7k7k小游戏</a>
                    <!-- 提示框 -->
                    <div class="tip-box">
                        7k7k7k小游戏7k7k7k小游戏7k7k7k小游戏7k7k7k小游戏7k7k7k小游戏7k7k7k小游戏7k7k7k小游戏
                    </div>
                </li>
            </ol>
        </div>
        <script>
            var ele_a = document.querySelectorAll(".title-list a");
            
            for(var i = 0; i < ele_a.length; i++){
                //鼠标移入时触发事件,显示提示框
                ele_a[i].addEventListener("mouseover", function( evt ){
                    var ele_tip = this.nextElementSibling;
                    ele_tip.style.display = "block"
                    var e = evt || event
                    ele_tip.style.left = e.pageX + "px";
                    //提示框和鼠标保持距离
                    ele_tip.style.top = e.pageY + 20 + "px"
                })
                //鼠标移动时,提示框跟着移动
                ele_a[i].addEventListener("mousemove", function( evt ){
                    var ele_tip = this.nextElementSibling;
                    var e = evt || event
                    ele_tip.style.left = e.pageX + "px";
                    ele_tip.style.top = e.pageY + 20 + "px"
                })
                //鼠标移出时,提示框消失
                ele_a[i].addEventListener("mouseout", function( evt ){
                    var ele_tip = this.nextElementSibling;
                    ele_tip.style.display = "none"
                })
            }
        </script>
    </body>
    </html>
    View Code

      以上就是用js实现的一些小案例,后续会更新一些新的小案例 ,希望能对伙伴们有帮助

      同时如果伙伴们有发现什么错误,请大家指点

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  • 原文地址:https://www.cnblogs.com/mz33/p/12500258.html
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