Getting Started with Node.js

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What is Node.js?

Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient. Node.js' package ecosystem, npm, is the largest ecosystem of open source libraries in the world.

Node.js vs Python

Print to Console "Fetching Info from Database"
Get Info from Database and Print to Console

Print to Console "Fetching Info from Website"
Get Info from Website and Print to Console

Node.js

Python

Fetching Info from Database
Fetching Info from Website
Website: Jeff
Database: Hello

Fetching Info from Database
Database: Hello
Fetching Info from Website
Website: Jeff

Node.js vs Python

Node.js

Python

. . .

db.query("SELECT * FROM people", def(names):
    for name in names:
        print(name)
)

. . .

db.query("SELECT * FROM people")

names = db.output;

for name in names:
    print(name)

The code on the left is not JavaScript! It is to show how callbacks work in JavaScript with Python code (which won't work in real life!).

NPM

NPM stands for Node Package Manager. It's the number one place to go to download Node packages (or libraries or modules).

Like pip for Python but better.

Trying it out!

Go to https://runkit.com/ and you should get a 'notebook':

run your code

write your code here

add a new code block (like a new file)

import library from npm

Syntax

Statements are separated by semicolons:

Comments:

var a = 5;
var b = 10;
var c;

c = a + b;

// Hello There! I'm a comment!

Printing to the Console

// Print Normal Text to the Console
console.log("Hello World");

Functions

function myFunction() {
    console.log("Hello!");
}

myFunction();
thisFunctionIsAfter();

function thisFunctionIsAfter() {
    console.log(`In Python, functions that are called before
        they are defined won't work. Will it in Node.js?`);
}

Functions with Arguments

parrot("hello");

function parrot(text) {
    console.log(text);
}

Importing Libraries

var name = require("library");

Input

var readline = require("readline");

var rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

rl.question("What do you think of Node.js? ", function(answer) {
    console.log("Thank you for your valuable feedback: ${answer}");
    
    //make sure to close when you've finished
    rl.close();
});

Input

Variables

var name = "Jeff";



console.log("Hello " + name);

console.log("Hello ${name}");

MySQL

Hey! MySQL sounds a bit like SQLite

You'd be right there! Both use SQL queries and they are both databases. MySQL databases are hosted on servers as opposed to inside a file. And the commands for MySQL are a little different to SQLite.

Getting Started

Import with:

var mysql = require("mysql");

Make a new connection:

var connection = mysql.createConnection({
    host: "carbon.vh7.uk",
    user: "codeclub",
    password: "icanhascheezburger",
    database: "codeclub"
});

Connect:

Disconnect:

connection.connect();

connection.end();

Executing Queries

Execute Queries

connection.query("SELECT * FROM people", function (error, results, fields) {
    if (error) throw error;
    
    results.forEach(function(result) {
        console.log(result.firstname);
    });
});

Databases

Challenges

• Add someone into the database.
• Add a new column to the database (e.g favanimal)
• Make a new table (e.g animals)
• Make a program which asks the user questions then inserts them into the database

Ask for help or Google what you want to do followed my MySQL (e.g "insert data mysql").