Web Technologies - Lecture 2

JAVASCRIPT 19

Web Technologies - Lecture 2 Guest on 28th February 2022 09:14:22 AM

NodeJS scenario is module based.
basic-server.js content:
// NOT PART of EXAM, ONLY FOR KNOWLEDGE
const http = require('http');
const router = (req, res)=>{
console.log('${req.method} ${req.url}')
res.writeHead(200, {'Content-Type':'text/html'}); // 200 means OK response, the type of response is text/html
res.end('<h1>Hello World</h1>');
}
const routes = {
'GET':{
'/':(req,res)=>{
res.writeHead(200, {'Content-Type':'text/html'}); // 200 means OK response, the type of response is text/html
// res.end('<h1>Hello World</h1>');
res.end(`<form method ="post">
<input type="text" name="username" placeholder="username">
<br>
<input type="password" name="password" placeholder="password">
<br>
<input type="submit" value="Login">
</form>`);
},
'about':(req,res)=>{
res.writeHead(200, {'Content-Type':'text/html'}); // 200 means OK response, the type of response is text/html
res.end('<h1>About Us</h1>');
}
},
'POST':{ '/':(req,res)=>{
let body = '';
req.on('data', (data)=>
{
body+=data;
});
req.on
}
},
'':()=>{}
}
// For Each is just for iteration, does not return any value
const router = (req, res)=>{
console.log('${req.method} ${req.url}')
let resolveRoute = routes[req.method][req.url]
if (resolveRoute !== undefined){
resolveRoute(req,res);
} else{
routes['NA'](req, res)
}
}
end of content
http
.createServer((req, res)=>{
res.writeHead(200, {'Content-Type':'text/html'}); // 200 means OK response, the type of response is text/html
res.end('<h1>Hello World</h1>');
})
.listen(3000, ()=> console.log('Server is running on http://localhost:3000')); // running on 3000 port
// NodeMon is used to sync the code, this will sync any changes whenever the code is changed so it does not require any kind of restart.
// GET and POST
// GET will receive
// POST will send the response
There are different types of modules
Dependency Module
Non-dependency Module (Does not do anything to the code, but provide support related to code such as NodeMon, monitors the code and syncs instantly
creating a module first
package.json file is created automatically
index.js - a module file
content:
constant express = require('express');
const app = express();
const port = 4000;
const logger = (req, res, next)=>{ // Next shows that it is a middleware, next means the next middleware to be executed.
req.msg = '/nThis message is from middleware!!!');
next();
}else{
res.send("Access denied")
}
}
const auth = (req, res, next)=>{
if (req.query.name === "Peter"){ // Query means GET, BODY means POST
next()
}
}
app.use(logger); // To use the middleware, we have to use this.
app.get('/', (req, res)=>{
res.send('<h3>Hello World</h3> ${msg}');
})
app.get('/users', auth, (req, res)=>{
res.send('<h3>Users Route</h3> ${msg}');
})
app.listen(port, ()=> console.log('Server is running on http://localhost:${port});
// There are different template engines
// The controller decides the route to go.

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NodeJS scenario is module based.

basic-server.js content:
// NOT PART of EXAM, ONLY FOR KNOWLEDGE

const routes = {
    'GET':{
        '/':(req,res)=>{
        
            res.writeHead(200, {'Content-Type':'text/html'});  // 200 means OK response, the type of response is text/html  
           // res.end('<h1>Hello World</h1>');
           res.end(`<form method ="post">
           <input type="text" name="username" placeholder="username">
           <br>
           <input type="password" name="password" placeholder="password">
           <br>
           <input type="submit" value="Login">
       </form>`);

},
    'about':(req,res)=>{
        res.writeHead(200, {'Content-Type':'text/html'});  // 200 means OK response, the type of response is text/html  
        res.end('<h1>About Us</h1>');  
    }
},
    'POST':{        '/':(req,res)=>{
        let body = '';
        req.on('data', (data)=>
        {
            body+=data;
        });
        req.on

}
    },
    '':()=>{}

}

// For Each is just for iteration, does not return any value

const router = (req, res)=>{
    console.log('${req.method} ${req.url}')
    let resolveRoute = routes[req.method][req.url]
    if (resolveRoute !== undefined){
        resolveRoute(req,res);
    } else{
        routes['NA'](req, res)
    }
}

end of content

http
.createServer((req, res)=>{
    res.writeHead(200, {'Content-Type':'text/html'});  // 200 means OK response, the type of response is text/html  
    res.end('<h1>Hello World</h1>');
})
.listen(3000, ()=> console.log('Server is running on http://localhost:3000')); // running on 3000 port

// NodeMon is used to sync the code, this will sync any changes whenever the code is changed so it does not require any kind of restart.
// GET and POST
// GET will receive
// POST will send the response

There are different types of modules
Dependency Module
Non-dependency Module (Does not do anything to the code, but provide support related to code such as NodeMon, monitors the code and syncs instantly

creating a module first

package.json file is created automatically

index.js - a module file
content:
constant express = require('express');
const app = express();
const port = 4000;

const logger = (req, res, next)=>{ // Next shows that it is a middleware, next means the next middleware to be executed.
req.msg =  '/nThis message is from middleware!!!');
next();
}else{
res.send("Access denied")
}
}

const auth = (req, res, next)=>{
if (req.query.name === "Peter"){ // Query means GET, BODY means POST
next()

}
}

app.use(logger); // To use the middleware, we have to use this.
app.get('/', (req, res)=>{
res.send('<h3>Hello World</h3> ${msg}');
})

app.get('/users', auth, (req, res)=>{
res.send('<h3>Users Route</h3> ${msg}');
})

app.listen(port, ()=> console.log('Server is running on http://localhost:${port});

// There are different template engines
// The controller decides the route to go.