The Basic of Node.JS (before Classes)

Well, if you are interested in the developer intern position at Fresno State DXI. Here is the very minimum required knowledge.

Must Watch Videos:

• https://youtu.be/TlB_eWDSMt4 ( Node.JS )
• https://youtu.be/gp5H0Vw39yw ( TypeScript )

Quick Assessments

PART ONE: Read a local JOSN file (data.json); find the user record of firstname = ‘jane’; capitalize the the first letter to ‘Jane’ ( not ALL records, just jane ); update the JSON object

data.json example from https://www.learningcontainer.com/sample-json-file/#JSON_file_example_1
{
 “users”: [
 {
 “userId”: 1,
 “firstName”: “Krish”,
 “lastName”: “Lee”,
 “phoneNumber”: “123456”,
 “emailAddress”: “krish.lee@learningcontainer.com”
 },
 {
 “userId”: 2,
 “firstName”: “racks”,
 “lastName”: “jacson”,
 “phoneNumber”: “123456”,
 “emailAddress”: “racks.jacson@learningcontainer.com”
 },
 {
 “userId”: 3,
 “firstName”: “denial”,
 “lastName”: “roast”,
 “phoneNumber”: “33333333”,
 “emailAddress”: “denial.roast@learningcontainer.com”
 },
 {
 “userId”: 4,
 “firstName”: “devid”,
 “lastName”: “neo”,
 “phoneNumber”: “222222222”,
 “emailAddress”: “devid.neo@learningcontainer.com”
 },
 {
 “userId”: 5,
 “firstName”: “jone”,
 “lastName”: “mac”,
 “phoneNumber”: “111111111”,
 “emailAddress”: “jone.mac@learningcontainer.com”
 }
 ]
}

Sample Solution (using ‘require’)

const database = require(‘./data.json’);
// Replace firstName jane with first lette capitalized
for(var key in database.users){
 if ( fn = database.users[key].firstName.match(/jone/) ){
 database.users[key].firstName = fn.input[0].toUpperCase() + fn.input.slice(1);
 }
}
console.log(database);

Output

jane is updated to Jane

PART TWO: Continue with Part One, but loading a remote JSON file ( https://jsontestfiles2022.s3.us-east-1.amazonaws.com/data.json )

Example Solution

const https = require('https');

let url = "https://jsontestfiles2022.s3.us-east-1.amazonaws.com/data.json";

https.get(url,(res) => {
    let body = "";

    res.on("data", (chunk) => {
        body += chunk;
    });

    res.on("end", () => {
        try {
            database = JSON.parse(body);
            for(var key in database.users){
                if ( fn = database.users[key].firstName.match(/jone/) ){
                    database.users[key].firstName = fn.input[0].toUpperCase() + fn.input.slice(1);
                }
            }
            console.log(database);
        } catch (error) {
            console.error(error.message);
        };
    });

}).on("error", (error) => {
    console.error(error.message);
});

PART THREE: Create and Load Module — app.js ( this main ) loading logger.js ( module ) to echo out a message

logger.js

function logger ( message ) {
    console.log(message);
}

module.exports = logger;

app.js

var log = require ('./logger3');

log('Part 3');

Output:

Part 3

PART FOUR: Events

1. register a Listener (messageLogged) to console log a JSON message
2. raise an Event (messageLogged) and send over an JSON of two elements id and name { id: 100, name: “Max }

const EventEmitter = require ('events');
const emitter = new EventEmitter();

// Register a Listener to console.log of the JSON object
emitter.on('messageLogged', ( noise ) => {
    console.log("Message Logged:  " + JSON.stringify(noise) );
})

// Raise an Event and passing  id and name
emitter.emit('messageLogged', {id: 100, name: "Max"});

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