前端业务开发中使用原生js和elementui两种方式实现头像裁切上传的功能

要实现头像裁剪上传的功能，可以使用现成的JavaScript库，例如cropperjs。以下是使用原生JavaScript和Element UI实现头像裁剪上传的简化示例：

1. 安装cropperjs和element-ui（如果还没有安装）：

npm install cropperjs element-ui --save

2. 在Vue组件中使用cropperjs和element-ui的Upload组件：

<template>
  <div>
    <el-upload
      action="http://example.com/upload"
      :show-file-list="false"
      :on-success="onSuccess"
      :before-upload="beforeUpload">
      <img v-if="imageUrl" :src="imageUrl" class="avatar" />
      <i v-else class="el-icon-plus avatar-uploader-icon"></i>
    </el-upload>
    <el-button @click="cropImage">裁剪图片</el-button>
  </div>
</template>
 
<script>
import Cropper from 'cropperjs';
import 'cropperjs/dist/cropper.css';
 
export default {
  data() {
    return {
      imageUrl: '',
      cropper: null,
      croppedBlob: null
    };
  },
  methods: {
    beforeUpload(file) {
      const reader = new FileReader();
      reader.onload = (e) => {
        const dataURL = e.target.result;
        this.initCropper(dataURL);
      };
      reader.readAsDataURL(file);
      return false; // 阻止默认上传行为
    },
    onSuccess(response, file, fileList) {
      // 上传成功后的处理逻辑
    },
    cropImage() {
      if (this.cropper) {
        this.croppedBlob = this.cropper.getCroppedBlob();
        const formData = new FormData();
        formData.append('file', this.croppedBlob, 'avatar.jpg');
        // 使用formData进行上传
        // axios.post('http://example.com/upload', formData)...
      }
    },
    initCropper(src) {
      const image = new Image();
      image.src = src;
      image.onload = () => {
        const cropperContainer = document.createElement('div');
        document.body.appendChild(cropperContainer);
        this.cropper = new Cropper(image, {
          aspectRatio: 1,
          viewMode: 1,
          dragMode: 'crop',
          autoCropArea: 1,
          movable: false,
          resizable: false,
          guides: false,
          center: false,
          highlight: false,
          cropBoxMovable: false,
          cropBoxResizable: false,
          toggleDragModeOnDblclick: false
        });
      };
    }
  }
};
</script>
 
<style>
.avatar-uploader .el-upload {
  border: 1px dashed #d9d9d9;
  border-radius: 6px;
  cursor: pointer;
  position: relative;
  overflow: hidden;
}
.avatar-uploader .el-upload:hover {
  border-color: #409eff;
}
.avatar-uploader-ic