js转换页面为图片并下载

 <div style="background:red;width: 600px;height: 600px;" class="test">
     <div id="imgs" style="background:green;">
         <div style="background:blue;">
             <div style="background:yellow;">
                 <div style="background:orange;">
                     33333333333333333333333333333333
                 </div>
             </div>

         </div>

     </div>
 </div>
 <h2 class="toCanvas"> <a href="javascript:void(0);"> 转成canvas </a></h2>
 <h2 class="toPic"><a href="javascript:void(0);"> 转成图片 </a></h2>
 <h5>
     <label for="imgW">宽度:</label>
     <input type="number" value="" id="imgW" placeholder="默认是原图宽度" />
     <label for="imgH">高度:</label>
     <input type="number" value="" id="imgH" placeholder="默认是原图高度" />
     <label for="imgFileName">文件名:</label>
     <input type="text" placeholder="文件名" id="imgFileName" />
     <select id="sel">
         <option value="png">png</option>
         <option value="jpeg">jpeg</option>
         <option value="bmp">bmp</option>
     </select>
     <button id="save">保存</button>
 </h5>

 * {
         margin:;
         padding:;
     }

     div {
         padding: 20px;
         border: 5px solid black;
     }

     h2 {
         background: #efefef;
         margin: 10px;
     }

     .toPic {
         display: none;
     }

 var test = $("#imgs")[0]; //将jQuery对象转换为dom对象
         // 点击转成canvas
         $('.toCanvas').click(function(e) {
             // 调用html2canvas插件
             html2canvas(test).then(function(canvas) {
                 // canvas宽度
                 var canvasWidth = canvas.width;
                 // canvas高度
                 var canvasHeight = canvas.height;
                 // 渲染canvas
                 $('.toCanvas').after(canvas);
                 // 显示‘转成图片’按钮
                 $('.toPic').show(1000);
                 // 点击转成图片
                 $('.toPic').click(function(e) {
                     // 调用Canvas2Image插件
                     var img = Canvas2Image.convertToImage(canvas, canvasWidth, canvasHeight);
                     // 渲染图片
                     $(".toPic").after(img);
                     // 点击保存
                     $('#save').click(function(e) {
                         let type = $('#sel').val(); //图片类型
                         let w = $('#imgW').val(); //图片宽度
                         let h = $('#imgH').val(); //图片高度
                         let f = $('#imgFileName').val(); //图片文件名
                         w = (w === '') ? canvasWidth : w; //判断输入宽高是否为空，为空时保持原来的值
                         h = (h === '') ? canvasHeight : h;
                         // 调用Canvas2Image插件
                         Canvas2Image.saveAsImage(canvas, w, h, type, f);
                     });
                 });

             });
         });

//demo地址:https://files.cnblogs.com/files/Zhushaoyu/html_img.zip