text: <html>
  
  <head>
      <meta charset="utf-8">
      <title>图片转换</title>
  </head>
  
  <body>
      <div style="width:80%;margin:0 auto;text-align:center">
          <canvas style="position: fixed; left:-100000px" id="canvas"></canvas>
          <input onchange="deal()" type="file" id="file" accept=".svg" multiple><br /><br />
          <!-- <input type="" -->
          <span>请输入图片后缀:</span><input id="filePostfix" type='text' value="bmp"><br /><br />
          <button onclick="startDeal()">开始处理</button>
      </div>
      <script>
          let arr = [];
  
          function deal() {
              let files = document.getElementById('file').files;
              for (let i = 0; i < files.length; i++) {
                  let reader = new FileReader();
                  reader.readAsText(files[i]);
                  reader.onload = function (e) {
                      arr.push({
                          name: files[i].name,
                          content: this.result
                      })
                  }
              }
          }
  
          function startDeal() {
              let postfix = document.getElementById('filePostfix').value;
              for (let i = 0; i < arr.length; i++) {
                  let item = arr[i];
                  console.log(`开始处理：${item.name}`);
                  let xml = new DOMParser().parseFromString(item.content, 'text/xml');
                  let svgContent = xml.getElementsByTagName('svg')[0].outerHTML;
                  let img = new Image();
                  img.src = 'data:image/svg+xml;base64,' + window.btoa(unescape(encodeURIComponent(svgContent)));
                  img.onload = function () {
                      let canvas = document.getElementById('canvas');
                      canvas.width = img.width;
                      canvas.height = img.height;
                      let ctx = canvas.getContext('2d')
                      ctx.drawImage(img, 0, 0, img.width, img.height, 0, 0, img.width, img.height);
                      let a = document.createElement('a')
                      a.href = canvas.toDataURL('image/' + postfix);
                      a.download = item.name.substr(0, item.name.lastIndexOf('.')) + '.' + postfix;
                      a.click();
                      if (i == arr.length - 1) {
                          console.log('处理完毕');
                          document.getElementById('file').value = '';
                          ctx.clearRect(0, 0, img.width, img.height);
                          arr = [];
                      }
                  }
              }
          }
      </script>
  
  </body>
  
  </html>