const pattern = new RegExp('src=(\'.+\'|".+")');
const html = `${parser
                  .makeHtml(res.content) //原本的markdown字符串
                  .split(/[ ]/) //空格分开
                  .map(el => { //分开后遍历 寻找img标签
                    //正则匹配
                    if(pattern.test(el)) {
                      const urls = el.split('=');
                      const url = urls[urls.length - 1].substr(1, urls[urls.length - 1].length - 2);
                      // eslint-disable-next-line no-param-reassign
                      // 绑定事件
                      return `${el} @click="showImgDialog('${url};')"`;
                    }
                    //不是img标签则直接返回
                    return el; 
                  })
                  .join(' ') //重新拼接成字符串
               }
               //增加模态框
               <el-dialog
                 :visible.sync="dialog.visible"
                 width="80%">
                 <el-row type="flex" justify="center">
                   <span>
                     <img :src="dialog.url"/>
                   </span>
                 </el-row>
               </el-dialog>`;