4dkankan-components/docs/examples-bk/upload/limit-cover.vue

<template>
    <el-upload ref="upload" class="upload-demo" action="https://run.mocky.io/v3/9d059bf9-4660-45f2-925d-ce80ad6c4d15" :limit="1" :on-exceed="handleExceed" :auto-upload="false">
        <template #trigger>
            <el-button type="primary">select file</el-button>
        </template>
        <el-button class="ml-3" type="success" @click="submitUpload"> upload to server </el-button>
        <template #tip>
            <div class="el-upload__tip text-red">limit 1 file, new file will cover the old file</div>
        </template>
    </el-upload>
</template>

<script setup lang="ts">
import { ref } from 'vue'
import { genFileId } from 'element-plus'
import type { UploadInstance, UploadProps, UploadRawFile } from 'element-plus'

const upload = ref<UploadInstance>()

const handleExceed: UploadProps['onExceed'] = files => {
    upload.value!.clearFiles()
    const file = files[0] as UploadRawFile
    file.uid = genFileId()
    upload.value!.handleStart(file)
}

const submitUpload = () => {
    upload.value!.submit()
}
</script>