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Detailed explanation of using nodejs+express to implement simple file upload function
Detailed explanation of using nodejs+express to implement simple file upload function
This article mainly introduces the simple file upload function using nodejs+express. Friends who need it can refer to it. I hope it can help everyone.
1. Create express project
express -e nodejs-uploadfile
2. Download multer middleware
npm i multer or yarn multer
3. Reference multer in routes/index.js. Since file operations are also used, you must also reference the fs module and specify the file upload directory
const multer = require('multer'); const fs = require('fs'); const UPLOAD_PATH = './uploads'
Single file upload: The files in index.html are as follows (the type of form file must be enctype="multipart/form-data"),
<form action="/upload" method="post" enctype="multipart/form-data"> <input name="fileUpload" type="file" /> <img src="" alt=""> <button type="submit">上传</button> </form>
Add the upload route in routes/index.js to handle the operation of uploading files
router.post('/upload', upload.single('fileUpload'), function (req, res, next) {
const { file } = req;
fs.readFile(file.path, function(err, data) {
fs.writeFile(`${UPLOAD_PATH}/${file.originalname}`, data, function (err) {
if (err) res.json({ err })
res.json({
msg: '上传成功'
});
});
})
})If the uploaded file is an image, also You can use the FileReader object to implement image preview
(function($){
$('input').on('change', function(event) {
var files = event.target.files,
reader = new FileReader();
if(files && files[0]){
reader.onload = function (ev) {
$('img').attr('src', ev.target.result);
}
reader.readAsDataURL(files[0]);
}
})
}(jQuery))Multiple file upload: The principle of multi-file upload is the same as that of single-file upload. The code is as follows:
router.post('/upload', upload.array('fileUpload'), function (req, res, next) {
const files = req.files;
const response = [];
const result = new Promise((resolve, reject) => {
files.map((v) => {
fs.readFile(v.path, function(err, data) {
fs.writeFile(`${UPLOAD_PATH}/${v.originalname}`, data, function(err, data) {
const result = {
file: v,
}
if (err) reject(err);
resolve('成功');
})
})
})
})
result.then(r => {
res.json({
msg: '上传成功',
})
}).catch(err => {
res.json({ err })
});
})Related codes are at github.com/bWhirring/n…
Related recommendations:
Detailed explanation of Ajax and node.js multer implementation files Upload function
Examples to explain thinkjs file upload function
jQuery implements preview function before uploading image files
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