const express = require("express");
const multer = require("multer");

const upload = multer({"dest": "./mult"});

const app = express();

app.get("/", indexHandler);
app.post("/save", upload.single("fileField"), saveHandler);

app.listen(3000, () => console.log("server started", 3000));

function indexHandler(req, res) {
    // enctype="multipart/form-data" is needed for file uploading.
    // fileField name matches the upload.single name
    var indexContent =
`<form action="/save" method="POST" enctype="multipart/form-data">
    <input type="file" name="fileField" />
    <button type="submit">Submit</button>
</form>`;
    res.status(200).type("html").send(indexContent);
}

function saveHandler(req, res) {
    console.log(req.file); // Since it's a single(), it uses .file variable
    res.status(200).type("text").send("File: " + JSON.stringify(req.file));
}