vue2.0 使用element-ui里的upload组件实现图片预览效果方法

<el-upload class="upload-demo" action="" :auto-upload='false' :on-change='changeUpload'> <el-button size="small" type="primary">点击上传</el-button> <div slot="tip" class="el-upload__tip">只能上传jpg/png文件，且不超过500kb</div></el-upload> 

changeUpload: function(file, fileList) { this.fileList = fileList; this.$nextTick(  () => {  let upload_list_li = document.getElementsByClassName('el-upload-list')[0].children;  for (let i = 0; i < upload_list_li.length; i++) {  let li_a = upload_list_li[i];  let imgElement = document.createElement("img");  imgElement.setAttribute('src', fileList[i].url);  imgElement.setAttribute('style', "max-width:50%;padding-left:25%");  if (li_a.lastElementChild.nodeName !== 'IMG') {   li_a.appendChild(imgElement);  }   }  }); }