Using MySQL with Javascript (node.js)

Question

I've just started learning Node.js. I come from a PHP background, so I started with MySQL. So, I wanted to try executing some basic MySQL queries using javaScript.I write the queries, this way:

filename: test.js

var mysql = require('mysql');
var con = mysql.createConnection({
  host: "localhost",
  user: "root",
  password: "",
  database: "test",
});
con.connect(err => {
  if (err) throw err;
  console.log("Connected!");
  const q = "INSERT INTO testing VALUES(3, 'MILLENNIAL', 19, 'STUDENT', 'CSE')";
  con.query(q, (err, result) => {
    if (err) throw err;
    console.log("done");
  });
});

When I run the only the javascript file this way: node test.js the query gets executed but when I connect the same file to a html file, this way:

<script src="test.js"></script>

the query doesn't get executed... It gives an error in console: Uncaught ReferenceError: require is not defined

I have feeling that I am not using something very important here. Am I missing something?? Please help me go further.

I am so sorry if this is very silly but, please help me with this. Thank you in advance.

The most important thing: there is no mysql in the browser. — aleksxor
– aleksxor, Commented Jul 2, 2021 at 18:22
Database connection should be in your back end only. Html file is for your front end. Your user should NOT be able to connect to the database directly — Aleksandrus
– Aleksandrus, Commented Jul 2, 2021 at 18:23
requirejs.org you may go through the steps as mentioned in the docs! — Uttam
– Uttam, Commented Jul 2, 2021 at 18:25

Eziz Hudayberdiyev · Accepted Answer · 2021-07-02 19:12:32Z

1

node.js is javascript runtime which uses javascript syntax, which is meant for server-side language. What you trying is to use nodejs script in frontend. require is not defined - because its applicable only for node, to use other modules in plain javascript you will need to use cdn or packages like browserify, webpack. Checkout docs if you are interested.

answered Jul 2, 2021 at 19:12

Eziz Hudayberdiyev

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David Harvey · Accepted Answer · 2021-07-02 19:15:28Z

I will try to explain from a PHP perspective.

When you write PHP, usually your resulting file is an HTML and you embed your PHP code in it, so it renders out without PHP to the requesting browser.

In node, this is different. We don't write the HTML with node code embedded. Node focuses more on backend and frontend separation. You write your backend to reply to your front end.

The backend is where you type var mysql = require('mysql');

You can use something like express vs koa to serve the resulting query to the front end.

Here's a good tutorial to start https://geshan.com.np/blog/2020/11/nodejs-mysql-tutorial/ I usually recommend Koa because it's up updated more regularly now, but express is basically the same thing!

Hope this directs you in the right direction.

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