Element-UI對于文件上傳組件的功能點著重于文件傳遞到后臺處理，所以要求action為必填屬性。
但是如果需要讀取本地文件并在前端直接處理，文件就沒有必要傳遞到后臺，比如在本地打開一個JSON文件，利用JSON文件在前端進行動態展示等等。
下面就展示一下具體做法：
首先定義一個jsonContent, 我們的目標是將本地選取的文件轉換為JSON賦值給jsonContent
然后我們的模板文件是利用el-dialog和el-upload兩個組件組合：這里停止文件自動上傳模式:auto-upload="false"
<el-button type="primary" @click="dialogVisible = true">Load from File</el-button> <el-dialog title="Load JSON document from file" :visible.sync="dialogVisible"> <el-upload :file-list="uploadFiles" action="alert" :auto-upload="false" multiple :on-change="loadJsonFromFile"> <el-button size="small" type="primary">Select a file</el-button> <div slot="tip">upload only jpg/png files, and less than 500kb</div> </el-upload> <span slot="footer"> <el-button type="primary" @click="dialogVisible = false">cancel</el-button> <el-button type="primary" @click="loadJsonFromFileConfirmed">confirm</el-button> </span> </el-dialog>
最后通過html5的filereader對變量uploadFiles中的文件進行讀取并賦值給jsonContent
if (this.uploadFiles) { for (let i = 0; i < this.uploadFiles.length; i++) { let file = this.uploadFiles[i] console.log(file.raw) if (!file) continue let reader = new FileReader() reader.onload = async (e) => { try { let document = JSON.parse(e.target.result) console.log(document) } catch (err) { console.log(`load JSON document from file error: ${err.message}`) this.showSnackbar(`Load JSON document from file error: ${err.message}`, 4000) } } reader.readAsText(file.raw) } }為方便測試，以下是完整代碼：
<template> <div> <el-button type="primary" @click="dialogVisible = true">Load from File</el-button> <el-dialog title="Load JSON document from file" :visible.sync="dialogVisible"> <el-upload :file-list="uploadFiles" action="alert" :auto-upload="false" multiple :on-change="loadJsonFromFile"> <el-button size="small" type="primary">Select a file</el-button> <div slot="tip">upload only jpg/png files, and less than 500kb</div> </el-upload> <span slot="footer"> <el-button type="primary" @click="dialogVisible = false">cancel</el-button> <el-button type="primary" @click="loadJsonFromFileConfirmed">confirm</el-button> </span> </el-dialog></div> </template> <script>export default { data () { return { // data for upload files uploadFilename: null, uploadFiles: [], dialogVisible: false } }, methods: { loadJsonFromFile (file, fileList) { this.uploadFilename = file.name this.uploadFiles = fileList }, loadJsonFromFileConfirmed () { console.log(this.uploadFiles) if (this.uploadFiles) { for (let i = 0; i < this.uploadFiles.length; i++) { let file = this.uploadFiles[i] console.log(file.raw) if (!file) continue let reader = new FileReader() reader.onload = async (e) => { try { let document = JSON.parse(e.target.result) console.log(document) } catch (err) { console.log(`load JSON document from file error: ${err.message}`) this.showSnackbar(`Load JSON document from file error: ${err.message}`, 4000) } } reader.readAsText(file.raw) } } this.dialogVisible = false } }}</script>PS： 相關閱讀
https://developer.mozilla.org/zh-CN/docs/Web/API/FileReader
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。
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