Upload file by fs writeFile with Node Js

uploadFile.js

const fs = require('fs');
const express = require('express');
const bodyParser = require('body-parser');
const path = require('path');
const app = express();
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: true}))
app.post('/upload-file', async function(req, res) {
    const fileName = req.body.fileName;
    const base64 = req.body.base64Data;
    console.log(base64);
    const file = fileName + '.'+'png';
    const bufferBase64 = Buffer.from(base64.replace(/^data:([A-Za-z-+\/]+);base64,/, ''), 'base64');
    const filePath = path.join(process.cwd() + '/uploads/' + file);
    console.log(filePath);
    return new Promise((resolve, reject) => {
        fs.writeFile(filePath, bufferBase64, 'base64', (err) => {
            if(err) {
                reject(err)
            } else {
                resolve('uploaded successfully');
            }
        })
    })
})
app.listen(3000, () => console.log('started server'));