需要限制input上传的文件大小

默认 `input` 上传文件的单位为 Byte (字节)

单位换算
1024Byte = 1KB
1024KB = 1MB
1024MB = 1GB

<el-form-item label ="上传文档：" prop="filePath">
    <input type="file" class="fl" id="batchImport" ref="batchImport" :accept="accept" name="batchImport" style="display: none;" @change="showWord($event)"/>
     <button id="upload" class="upload_btn" type="button" @click="uploadWord">请选择文档</button>
     <span id="document_name">{{wordResult}}</span>
     <div class="el-form-item__error" v-if="isError">请选择上传文档</div>
</el-form-item>

const file = document.getElementById('batchImport').files[0]
const fileMaxSize = 1024*1024*100
if (file.size > fileMaxSize) {
    this.$utils.showTip('error','','文档大小不超过100M！','文档大小不超过100M！')
} else {
    uploadReport(this);
}