<style>
  .upload-tip {
    color: #8492a6;
    font-size: 12px;
    margin-top: 7px;
  }
  .demo-box {
    margin-bottom: 24px;

    .upload-demo {
      width: 360px;
    }
    .avatar-uploader {
      .el-upload {
        border: 1px dashed #d9d9d9;
        border-radius: 6px;
        cursor: pointer;
        position: relative;
        overflow: hidden;

        &:hover {
          border-color: #20a0ff;
        }
      }
      .avatar-uploader-icon {
        font-size: 28px;
        color: #8c939d;
        width: 178px;
        height: @width;
        line-height: @height;
        text-align: center;
      }
      .avatar {
        width: 178px;
        height: @width;
        display: block;
      }
    }
  }
</style>
<script>
  export default {
    data() {
      return {
        fileList: [{
          name: 'food.jpeg',
          url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100',
          status: 'finished'
        }, {
          name: 'food2.jpeg',
          url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100',
          status: 'finished'
        }],
        fileList2: [{
          name: 'food.jpeg',
          url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100',
          status: 'finished'
        }, {
          name: 'food2.jpeg',
          url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100',
          status: 'finished'
        }],
        fileList3: [{
          name: 'food.jpeg',
          url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100',
          status: 'finished'
        }, {
          name: 'food2.jpeg',
          url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100',
          status: 'finished'
        }],
        imageUrl: '',
        dialogImageUrl: '',
        dialogVisible: false
      };
    },
    methods: {
      handleRemove(file, fileList) {
        console.log(file, fileList);
      },
      beforeUpload(file) {
        if (file.size > 40000000) {
          console.warn(file.name + ' is too large!');
          return false;
        }
        return true;
      },
      handlePreview(file) {
        console.log(file);
      },
      handlePictureCardPreview(file) {
        this.dialogImageUrl = file.url;
        this.dialogVisible = true;
      },
      submitUpload() {
        this.$refs.upload.submit();
      },
      handleAvatarScucess(res, file) {
        this.imageUrl = URL.createObjectURL(file.raw);
      },
      beforeAvatarUpload(file) {
        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;
      },
      handleChange(file, fileList) {
        this.fileList3 = fileList.slice(-3);
      }
    }
  }
</script>

## Upload 上传

通过点击或者拖拽上传文件

### 点击上传

::: demo 通过 slot 你可以传入自定义的上传按钮类型和文字提示。
```html
<el-upload
  class="upload-demo"
  action="//jsonplaceholder.typicode.com/posts/"
  :on-preview="handlePreview"
  :on-remove="handleRemove"
  :file-list="fileList">
  <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>
<script>
  export default {
    data() {
      return {
        fileList: [{name: 'food.jpeg', url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100'}, {name: 'food2.jpeg', url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100'}]
      };
    },
    methods: {
      handleRemove(file, fileList) {
        console.log(file, fileList);
      },
      handlePreview(file) {
        console.log(file);
      }
    }
  }
</script>
```
:::

### 用户头像上传

使用 `before-upload` 限制用户上传的图片格式和大小。

::: demo
```html
<el-upload
  class="avatar-uploader"
  action="//jsonplaceholder.typicode.com/posts/"
  :show-file-list="false"
  :on-success="handleAvatarScucess"
  :before-upload="beforeAvatarUpload">
  <img v-if="imageUrl" :src="imageUrl" class="avatar">
  <i v-else class="el-icon-plus avatar-uploader-icon"></i>
</el-upload>
<script>
  export default {
    data() {
      return {
        imageUrl: ''
      };
    },
    methods: {
      handleAvatarScucess(res, file) {
        this.imageUrl = URL.createObjectURL(file.raw);
      },
      beforeAvatarUpload(file) {
        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;
      }
    }
  }
</script>
```
:::

### 照片墙

使用 `list-type` 属性来设置文件列表的样式。

::: demo
```html
<el-upload
  action="//jsonplaceholder.typicode.com/posts/"
  list-type="picture-card"
  :on-preview="handlePictureCardPreview"
  :on-remove="handleRemove">
  <i class="el-icon-plus"></i>
</el-upload>
<el-dialog v-model="dialogVisible" size="tiny">
  <img width="100%" :src="dialogImageUrl" alt="">
</el-dialog>
<script>
  export default {
    data() {
      return {
        dialogImageUrl: '',
        dialogVisible: false
      };
    },
    methods: {
      handleRemove(file, fileList) {
        console.log(file, fileList);
      },
      handlePictureCardPreview(file) {
        this.dialogImageUrl = file.url;
        this.dialogVisible = true;
      }
    }
  }
</script>
```
:::

### 图片列表缩略图

::: demo
```html
<el-upload
  class="upload-demo"
  action="//jsonplaceholder.typicode.com/posts/"
  :on-preview="handlePreview"
  :on-remove="handleRemove"
  :file-list="fileList2"
  list-type="picture">
  <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>
<script>
  export default {
    data() {
      return {
        fileList2: [{name: 'food.jpeg', url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100'}, {name: 'food2.jpeg', url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100'}]
      };
    },
    methods: {
      handleRemove(file, fileList) {
        console.log(file, fileList);
      },
      handlePreview(file) {
        console.log(file);
      }
    }
  }
</script>
```
:::

### 上传文件列表控制

通过 `on-change` 钩子函数来对列表进行控制

::: demo
```html
<el-upload
  class="upload-demo"
  action="//jsonplaceholder.typicode.com/posts/"
  :on-change="handleChange"
  :file-list="fileList3">
  <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>
<script>
  export default {
    data() {
      return {
        fileList3: [{
          name: 'food.jpeg',
          url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100',
          status: 'finished'
        }, {
          name: 'food2.jpeg',
          url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100',
          status: 'finished'
        }]
      };
    },
    methods: {
      handleChange(file, fileList) {
        this.fileList3 = fileList.slice(-3);
      }
    }
  }
</script>
```
:::

### 拖拽上传

::: demo
```html
<el-upload
  class="upload-demo"
  drag
  action="//jsonplaceholder.typicode.com/posts/"
  mutiple>
  <i class="el-icon-upload"></i>
  <div class="el-upload__text">将文件拖到此处，或<em>点击上传</em></div>
  <div class="el-upload__tip" slot="tip">只能上传jpg/png文件，且不超过500kb</div>
</el-upload>
```
:::

### 手动上传

::: demo
```html
<el-upload
  class="upload-demo"
  ref="upload"
  action="//jsonplaceholder.typicode.com/posts/"
  :on-preview="handlePreview"
  :on-remove="handleRemove"
  :file-list="fileList"
  :auto-upload="false">
  <el-button slot="trigger" size="small" type="primary">选取文件</el-button>
  <el-button style="margin-left: 10px;" size="small" type="success" @click="submitUpload">上传到服务器</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>
<script>
  export default {
    data() {
      return {
        fileList: [{name: 'food.jpeg', url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100'}, {name: 'food2.jpeg', url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100'}]
      };
    },
    methods: {
      handleRemove(file, fileList) {
        console.log(file, fileList);
      },
      handlePreview(file) {
        console.log(file);
      }
    }
  }
</script>
```
:::

### Attribute
| 参数      | 说明          | 类型      | 可选值                           | 默认值  |
|---------- |-------------- |---------- |--------------------------------  |-------- |
| action | 必选参数, 上传的地址 | string | — | — |
| headers | 可选参数, 设置上传的请求头部 | object | — | — |
| multiple | 可选参数, 是否支持多选文件 | boolean | — | — |
| data | 可选参数, 上传时附带的额外参数 | object | — | — |
| name | 可选参数, 上传的文件字段名 | string | — | file |
| with-credentials | 支持发送 cookie 凭证信息 | boolean | — | false |
| show-file-list | 是否显示已上传文件列表 | boolean | — | true |
| type | 上传控件类型 | string | select,drag | select |
| accept | 可选参数, 接受上传的[文件类型](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input#attr-accept)（thumbnail-mode 模式下此参数无效）| string | — | — |
| on-preview | 可选参数, 点击已上传的文件链接时的钩子, 可以通过 file.response 拿到服务端返回数据 | function(file) | — | — |
| on-remove | 可选参数, 文件列表移除文件时的钩子 | function(file, fileList) | — | — |
| on-success | 可选参数, 文件上传成功时的钩子 | function(response, file, fileList) | — | — |
| on-error | 可选参数, 文件上传失败时的钩子 | function(err, file, fileList) | — | — |
| on-progress | 可选参数, 文件上传时的钩子 | function(event, file, fileList) | — | — |
| on-change | 可选参数, 文件状态改变时的钩子，上传成功或者失败时都会被调用 | function(file, fileList) | — | — |
| before-upload | 可选参数, 上传文件之前的钩子，参数为上传的文件，若返回 false 或者 Promise 则停止上传。 | function(file) | — | — |
| list-type | 文件列表的类型 | string | text/picture/picture-card | text |
| auto-upload | 是否在选取文件后立即进行上传 | boolean | — | true |
| file-list | 上传的文件列表, 例如: [{name: 'food.jpeg', url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100'}] | array | — | [] |

### Methods
| 方法名      | 说明          | 参数 |
|---------- |-------------- | -- |
| clearFiles | 清空已上传的文件列表 | — |
