To read file into a base64 string in Node.js, we call the readFile method.
For instance, we write
const fs = require("fs").promises;
const contents = await fs.readFile("/path/to/file.jpg", { encoding: "base64" });
to call the readFile method to read the /path/to/file.jpg file into a base64 string by setting the encoding option to 'base64'.
To add MySQL connection pooling with Node.js, we use the createPool method.
For instance, we write
const mysql = require("mysql");
const pool = mysql.createPool({
host: "localhost",
user: "root",
password: "root",
database: "guess",
});
pool.getConnection((err, connection) => {
callback(err, connection);
});
to call createPool to create a connection pool.
Then we call pool.getConnection to get a connection and make queries with it.
To upload images using Node.js, Express, and Mongoose, we use the express.multipart method.
For instance, we write
const express = require("express");
const http = require("http");
const app = express();
app.use(express.static("./public"));
app.use(express.methodOverride());
app.use(
express.multipart({
uploadDir: "./uploads",
keepExtensions: true,
})
);
app.use(app.router);
app.get("/upload", (req, res) => {
res.render("upload");
});
app.post("/upload", (req, res) => {
res.json(req.files);
});
http.createServer(app).listen(3000, () => {
console.log("App started");
});
to call express.multipart to return a middleware function that accepts uploads.
And then we get the uploaded file from req.files in the /upload route handler.
We use express.static to expose the /public folder as a static file folder.
To fix the "Cannot find module ‘@babel/core’" with JavaScript, we install the @babel/core package.
For instance, we run
npm install @babel/core --save
to install the @babel/core package with npm and save it into package.json.
To fix "cannot find module ‘request’" error with Node.js, we install the request package.
To install it, we run
npm install request --save
Then we can use it with
const request = require("request");
request("http://www.example.com", (error, response, body) => {
if (!error && response.statusCode === 200) {
console.log(body);
}
});
We call request to make a get request to http://www.example.com
And get the response with response from the callback.