vue中element 上传功能的实现思路

// template
<el-upload 
 class="avatar-uploader" 
 action="https://jsonplaceholder.typicode.com/posts/" 
 :show-file-list="false" 
 :on-success="handleAvatarSuccess" 
 :before-upload="beforeAvatarUpload">
 <img v-if="imageUrl" :src="imageUrl" class="avatar">
 <i v-else class="el-icon-plus avatar-uploader-icon"></i>
</el-upload>
// javscript
data() {
 return {
  imageUrl: ""
 };
 },
 methods: {
 handleAvatarSuccess(res, file) {
  this.imageUrl = URL.createObjectURL(file.raw);
 },
 beforeAvatarUpload(file) {
  // 文件类型进行判断 
  const isJPG = file.type === "image/jpeg";
  const isLt2M = file.size / 1024 / 1024 < 2;
  if (!isJPG) {
  this.$message.error("上传头像图片只能是 JPG 格式!");
  }
  if (!isLt2M) {
  this.$message.error("上传头像图片大小不能超过 2MB!");
  }
  return isJPG && isLt2M;
 }
 }

async beforeAvatarUpload(file) {
  const isSubmit = await this.$confirm('此操作将上传文件, 是否继续?', '提示', {
   confirmButtonText: '确定',
   cancelButtonText: '取消',
   type: 'warning'
  }).then(() => {
   return true
  }).catch(() => { 
   return false  
  });
  console.log(isSubmit)
  return isSubmit;
 }

auto-upload
on-change
// template
<el-upload 
 ref="upload"
 class="upload-demo" 
 action="https://jsonplaceholder.typicode.com/posts/" 
 :on-preview="handlePreview" 
 :limit="1" 
 :auto-upload="false"
 :on-change="handleChange"
 :show-file-list="true" 
 :file-list="fileList"
 :on-error="handleError"
 :on-success="handleSuccess">
 <el-button size="small" type="primary">点击上传</el-button>
</el-upload>
// js
data() {
return {
 fileList: [
 ],
 bool: true
 }
},
methods: {
 handleRemove(file, fileList) {
 console.log(file, fileList);
 },
 handlePreview(file) {
 console.log(file);
 },
 handleError(err, file) {
  alert('失败')
  this.fileList = []
 },
 handleSuccess(res, file) {
 alert('成功')
 this.fileList = []
 },
 handleExceed(files, fileList) {},
 async handleChange() {
 const isSubmit = await this.$confirm('此操作将永久删除该文件, 是否继续?', '提示', {
  confirmButtonText: '确定',
  cancelButtonText: '取消',
  type: 'warning'
 }).then(() => {
  return false
 }).catch(() => { 
  return true  
 });
 if (isSubmit) {
  this.$refs.upload.submit() 
 } else {
  this.fileList = []
 }
 } 
}

data() {
 return {
 isConfirm: true
 }
}
async handleChange() {
 if (!this.isConfirm) {
 this.isConfirm = true
 return
 }
 const bo = await this.$confirm('此操作将永久删除该文件, 是否继续?', '提示', {
 confirmButtonText: '确定',
 cancelButtonText: '取消',
 type: 'warning'
 }).then(() => {
 return false
 }).catch(() => { 
 return true  
 })
 if (bo) {
 this.$refs.upload.submit()
 this.isConfirm = false
 } else {
 this.fileList = []
 }
}