Node Programming Examples

Node.js Events example

node

var events = require('events');
var eventEmitter = new events.EventEmitter();

// listener #1
var listner1 = function listner1() {
   console.log('listner1 executed.');
}

// listener #2
var listner2 = function listner2() {
  console.log('listner2 executed.');
}

// Bind the connection event with the listner1 function
eventEmitter.addListener('connection', listner1);

// Bind the connection event with the listner2 function
eventEmitter.on('connection', listner2);

var eventListeners = require('events').EventEmitter.listenerCount
   (eventEmitter,'connection');
console.log(eventListeners + " Listner(s) listening to connection event");

// Fire the connection event 
eventEmitter.emit('connection');

// Remove the binding of listner1 function
eventEmitter.removeListener('connection', listner1);
console.log("Listner1 will not listen now.");

// Fire the connection event 
eventEmitter.emit('connection');

eventListeners = require('events').EventEmitter.listenerCount(eventEmitter,'connection');
console.log(eventListeners + " Listner(s) listening to connection event");

console.log("Program Ended.");

aa1234

node

/* Hello, World! program in node.js */
console.log("Hello, World!")

Execute Node.js Online

node

/* Simple Hello World in Node.js */
/*
console.log("Hola mundo");
var x=1
console.log(x)
var nombre="Marcelo"
console.log(nombre)
let nacionalidad="Peruano"
console.log(nacionalidad)
let operando1=10
let operando2=15
console.log(operando1)
console.log(operando2)
var resultado=operando1+operando2
console.log(resultado)
var multiplicacion=operando1*operando2
console.log(multiplicacion)*/



/*var a=10 //defino mi variable a, con el valor 10
var b=20 //defino mi variable b, con el valor 20

let multiplicacion = (x,y)=>  //creo la funcion llamada multiplicacion, la //funcion necesita 2 valores x, y 
{
    return x*y    //la funcion realiza un calculo y devuelve el resultado de ese calculo
}

console.log(   multiplicacion(a,b)    )



var sumando1=10 //definiendo mis variables con sus valores
var sumando2=30

let sumatoria = (a,b) =>
{
    return a+b
}

console.log(   sumatoria(sumando1,sumando2)   )



var minuendo=90
var sustraendo=50

let resta = (parametro1,parametro2) =>
{
    console.log(parametro1)
    console.log(parametro2)
    return parametro1-parametro2
}

console.log(   resta(minuendo,sustraendo)   )


var dividendo=64
var divisor=8

let division = (par1,par2) =>
{
    return (par1/par2)*3
}

console.log( division(dividendo,divisor))*/


var total=90
var unitario=8

let cortes = (par1,par2) =>
{
     return "marcelo" //(par1/par2)-1
}

console.log( cortes (total,unitario))

name

node

/* Hello, World! program in node.js */
console.log("Hello from sourabh!")

Node.js Hello World Example

node

 //Import events module
var events = require('events');

// Create an eventEmitter object
var eventEmitter = new events.EventEmitter();

// Create an event handler as follows
var connectHandler = function connected() {
   console.log('connection succesful.');
  
   // Fire the data_received event 
   eventEmitter.emit('data_received');
}

// Bind the connection event with the handler
eventEmitter.on('connection', connectHandler);
 
// Bind the data_received event with the anonymous function
eventEmitter.on('data_received', function() {
   console.log('data received succesfully.');
});

// Fire the connection event 
eventEmitter.emit('connection');

console.log("Program Ended.");

testcatch

node

/* Simple Hello World in Node.js */
console.log("Hello World");
try {
    throw Error('hahaha')
} catch (err) {
    console.log("Instruction 1")
    console.error("inst 2")
}

promisfigge

node

function getMembers() {
    return new Promise((resolve) => {
        resolve(10);
    });
}

var count;
getMembers().then((c) => {
    count = c; 
});
console.log("directly after:", count);
setTimeout(() => console.log("after 10 ms:   ", count), 10);

Execute Node.js Online

node

//models/user.js


const mongoose=require('mongoose');

const userSchema=mongoose.Schema({
    _id: mongoose.Schema.Types.ObjectId,
    email:{type:String,
    required:true,
    unique:true,
    match:/^([\w-\.]+@([\w-]+\.)+[\w-]{2,4})?$/
    },
    password:{typr:String,required:true}
});
module.exports=mongoose.model('User',userSchema);



//api/user.js

const mongoose=require('mongoose');
const express=require('express');
const router=express.Router();
const bcrypt=require('bcrypt');
const jwt=require('jsonwebtoken');

const User=require("../models/user");

router.post('/signup',(req,res,next)=>{
    User.find({
        email:req.body.email
    })
    .exec().
    then(user=>{
        if(user.length>=1){
            return res.status(409).json({
               message:"Mail exits" 
            });
        }
        else{
               bcrypt.hash(req.body.password,10,(err,hash)=>{
            if(err){
                return res.status(401).json({
                    error:err
                });
            }
            else{
               const user=new User({
        _id:new mongoode.Types.ObjectId(),
        email:req.body.email,
        password:hash
        }); 
        user
        .save()
        .then(result=>{
         console.log(result);
         res.status(201).json({
            message:'User Created'
         });
         
        })
        .catch(err=>{
           console.log(err);
           res.status(500).json({
              error:err 
           });
        });
            }
        });
        }
    });
 
    
});


router.delete("./:userId",(req,res,next)=>{
   User.remove({_id:req.params.userId})
   .exec()
   .then(result=>{
      res.status(200).json({
          message:"User deletion"
      });
   })
   .catch(err=>{
       console.log(err);
      res.status(500).json({
         error:err 
      }); 
   });
});


router.post("/login",(req,res,next)=>{
   User.find({email:req.body.email})
   .exec()
   .then(user=>{
       if(user.length<1){
           return res.status(401).json({
              message:"Auth failed" 
           });
       }
     
           bcrypt.compare(req.body.password,user[0].password,(err,res)=>{
              if(err){
                  return res.status(401).json({
                     message:"Auth failed"
                  });
              } 
              if(result){
                 const token= jwt.sign(
                      {
                          email:user[0].email,
                          userId:user[0]._id
                      },
                      process.env.JWT_KEY,
                      {
                          expiresIn:"1h"
                      }
                      );
                  
                  
                  
                 return res.status(200).json({
                    message:"Auth Successful", 
                    token:token
                 }); 
              }
         res.status(401).json({
                     message:"Auth failed"
                  });
           }); 
   })
   .catch(err=>{
      console.log(err);
      return res.status(500).json({
         error:err 
      });
   });
});
module.exports=router;





//middleware/check-auth.js


const jwt=require('jsonwebtoken');

module.exports= (req,res,next)=>{
    try{
        const token=req.headers.authorization.split(" ")[1];
        const decoded=jwt.verify(token,process.env.JWT_KEY);
        //const decoded=jwt.verify(req.body.token,process.env.JWT_KEY);
        req.userData=decoded;
        next();
    }
    catch(error){
        return res.status(401).json({
           message:'Auth failed' 
        });
    }
};


//authentication.js


var passport = require('passport');
var mongoose = require('mongoose');
var User = mongoose.model('User');
const express=require('express');
var path = require('path');
var hbs = require('nodemailer-express-handlebars');
var nodemailer = require('nodemailer');
var   async = require('async');

 require('dotenv').load();

var email = process.env.MAILER_EMAIL_ID || '[email protected]';
var pass = process.env.MAILER_PASSWORD || 'auth_email_pass';

var fullUrl;

var smtpTransport = nodemailer.createTransport({
  service: process.env.MAILER_SERVICE_PROVIDER || 'Gmail',
  auth: {
    user: email,
    pass: pass
  },
  tls: {
    rejectUnauthorized: false
}
});


var handlebarsOptions = {
  viewEngine: {
    extname: '.html',
    partialsDir : path.resolve('./server/partials')
},
  viewPath: path.resolve('./server/templates/'),
  extName: '.html'
};

smtpTransport.use('compile', hbs(handlebarsOptions));


/**
 * Forgot password
 */
exports.forgot_password = function(req, res) {
  fullUrl  = req.protocol + '://' + req.get('host') ;
  var token;
  async.waterfall([
    function(done) {
      User.findOne({
        email: req.body.email
      }).exec(function(err, user) {
        if (user) {
          token=user.token;
          done(err, user);
        } else {
          done('User not found.');
        }
      });
    },
  
    function( user, done) {
      var data = {
        to: user.email,
        from: email,
        template: 'forgot-password-email',
        subject: 'Password help has arrived!',
        context: {
          url:  fullUrl+'/reset_password?token=' + token+'&email='+user.email,
          name: user.firstName
        }
      };
    
      smtpTransport.sendMail(data, function(err) {
        if (!err) {
          return res.json({ message: 'Kindly check your email for further instructions' });
        } else {
          return  res.status(422).json({ message: "Mail Cannot be sent" });
        }
      });
    }
  ], function(err) {
    console.log(err);
    return done.status(422).json({ message: "User not found" });
  });
};

/**
 * Reset password
 */
exports.reset_password = function(req, res, next) {
  User.findOne({
    email: req.body.email
  }).exec(function(err, user) {
    if (!err && user) {
      if (req.body.newPassword === req.body.confirmPassword) {
        user.setPassword(req.body.newPassword);
        var token;
        token = user.generateJwt();
       user.token=token;
        user.save(function(err) {
          if (err) {
            return res.status(422).send({
              message: "Some error occured"
            });
          } else {
            
            var data = {
              to: user.email,
              from: email,
              template: 'reset-password-email',
              subject: 'Password Reset Confirmation',
              context: {
                name: user.firstName
              }
            };

            smtpTransport.sendMail(data, function(err) {
              if (!err) {
                return res.json({ "token":token });
              } else {
                return done.status(422).send({
                  message: "Some error occured"
                });
              }
            });
           
          }
        });
      } else {
        return res.status(422).send({
          message: 'Passwords do not match'
        });
      }
    } else {
      console.log(err);
      return res.status(400).send({
        message: 'Some error occured.'
      });
    }
  });
};


var sendJSONresponse = function(res, status, content) {
  res.status(status);
  res.json(content);
};

/*
Register
*/
module.exports.register = function(req, res) {
 
   if(!req.body.firstName || !req.body.email || !req.body.password || !req.body.lastName || !req.body.phone) {
    sendJSONresponse(res, 400, {
      "message": "All fields required"
    });
    return;
   }

   User.find({
    email:req.body.email
})
.exec().
then(user=>{
    if(user.length>=1){
        return res.status(409).json({
           message:"Mail exits" 
        });
    }
  
    else{
  var user = new User();

  user.email = req.body.email;
  user.firstName=req.body.firstName;
  user.lastName=req.body.lastName;
  user.phone=req.body.phone;

  user.setPassword(req.body.password);
  var token;
  token = user.generateJwt();
  user.token=token;
  user.save(function(err) {
   
  
if(!err){
    res.status(200);
    res.json({
      "token" : token,
      "message":"User Created"
    });
  }
  else{
    console.log(err);
    res.status(500).json({
       error:err 
    });
  }
  });
    }
  });
};

/*
Login
*/
module.exports.login = function(req, res) {

  if(!req.body.email || !req.body.password) {
    sendJSONresponse(res, 400, {
      "message": "All fields required"
    });
    return;
  }

  passport.authenticate('local', function(err, user, info){
    var token;

    // If Passport throws/catches an error
    if (err) {
      res.status(404).json(err);
      return;
    }

    // If a user is found
    if(user){
      token = user.generateJwt();
      user.token=token;
      user.save(function(err) {   

      });
      res.status(200);
      res.json({
        "token" : token
      });
    } else {
      // If user is not found
      res.status(401).json(info);
    }
  })(req, res);

};


module.exports.getToken = function(req, res) {
  User.findOne({
    email: req.body.email
  }).exec(function(err, user) {
    if (!err && user) {
      var token=user.token;
      res.status(200);
    res.json({
      "token" : token
    });
    }
    else{
      console.log(err);
      return res.status(400).send({
        message: 'Error in authentication'
      });
    }
    });

}



//videos.js



const express=require('express');
const router=express.Router();
const mongoose=require('mongoose');
const Video=require('../models/video');
var jwt = require('express-jwt');



exports.allVideos = function(req, res) {
    console.log('Get request for all videos');
Video.find({})
.exec(function(err,videos){
    if(err){
        console.log('Error retrieving videos');
    res.status(500).json({
       error:err ,
       message:"Error retrieving videos",
    });

    }
    else{
        res.json(videos);
    }

});
};


exports.videoById=function(req,res){
    console.log('Get request for single video');
    Video.findById(req.params.id)
    .exec(function(err,video){
        if(err){
            console.log('Error retrieving video');
            res.status(500).json({
               error:err ,
               message:"Error retrieving video",
            });
        }
        else{
            res.json(video);
        }
    
    });
    };


exports.postVideo=function(req,res){
    console.log('Post a video');
var newVideo=new Video();
newVideo.title=req.body.title;
newVideo.description=req.body.description;
newVideo.url=req.body.url;
newVideo.save(function(err,insertedVideo){
if(err){
    console.log('Error in posting video');
    res.status(500).json({
       error:err ,
       message:"Error in posting video",
    });
}
else{
    res.json(insertedVideo);
}
});
  
    };



exports.updateVideo=function(req,res){
    console.log('Updating a video');
    Video.findByIdAndUpdate(req.params.id,
    {
        $set:{title:req.body.title,url:req.body.url,description:req.body.description}
    },
    {
        new:true
    },function(err,updatedVideo){
        if(err){
            console.log('Error in updating video');
            res.status(500).json({
               error:err ,
               message:"Error in updating video",
            });
        }
        else{
            res.json(updatedVideo);
        }
    }
    );
      
        };


exports.deleteVideo=function(req,res){
    console.log('Deleting a video');
    Video.findByIdAndRemove(req.params.id,function(err,deletedVideo){
        if(err){
            console.log('Error in deleting video');
            res.status(500).json({
               error:err ,
               message:"Error in deleting video",
            });
        }
        else{
            res.json(deletedVideo);
        }
    });
};




//forgot-password.ts



import { Component, OnInit } from '@angular/core';
import { Router } from '@angular/router';
import { AuthenticationService,ForgotTokenPayload} from '../authentication.service';
import { NgForm } from '@angular/forms';
@Component({
  selector: 'app-forgot-password',
  templateUrl: './forgot-password.component.html',
  styleUrls: ['./forgot-password.component.css']
})
export class ForgotPasswordComponent implements OnInit {

  credentials: ForgotTokenPayload = {
    email: '',
  
  };

  constructor(private auth: AuthenticationService, private router: Router) { }

  ngOnInit() {
  }
  forgot_password(userForm: NgForm) {
    this.credentials.email=userForm.controls['email'].value;
 
    this.auth.forgotPassword(this.credentials).subscribe(() => {
      this.router.navigateByUrl('/login');
    }, (err) => {
      console.error(err);
    }); 
  }
}



//login.ts


import { Component, OnInit } from '@angular/core';
import { AuthenticationService, LoginTokenPayload } from '../authentication.service';
import { Router } from '@angular/router';
import { NgForm } from '@angular/forms';

@Component({
  selector: 'app-login',
  templateUrl: './login.component.html',
  styleUrls: ['./login.component.css']
})
export class LoginComponent implements OnInit {

 

  ngOnInit() {
  }
  credentials: LoginTokenPayload = {
    email: '',
    password: ''
  };

  constructor(private auth: AuthenticationService, private router: Router) {}

  login(userForm: NgForm) {
    this.credentials.email=userForm.controls['email'].value;
    this.credentials.password=userForm.controls['password'].value;
    this.auth.login(this.credentials).subscribe(() => {

      this.router.navigateByUrl('/home');
    }, (err) => {
      console.error(err);
    }); 
  }
}


//home.ts

import { Component, OnInit } from '@angular/core';
import { AuthenticationService } from '../authentication.service';
@Component({
  selector: 'app-home',
  templateUrl: './home.component.html',
  styleUrls: ['./home.component.css']
})
export class HomeComponent implements OnInit {

  constructor(private auth: AuthenticationService) { }

  ngOnInit() {
  }
logout(){
this.auth.logout();
}
}





https://stackoverflow.com/questions/48275052/angular-2-navigate-to-home-page-on-browser-back-refresh-button-clicks






<ul class="nav navbar-nav navbar-right">
      <li><a href="#"><span class="glyphicon glyphicon-user"></span> Sign Up</a></li>
      <li><a href="#"><span class="glyphicon glyphicon-log-in"></span> Login</a></li>
    </ul>

Execute stringsIncludes Online

node

var x  = 0;
var myJsonObj = {"page":2,"per_page":3,"total":12,"total_pages":4,"data":[{"id":4,"first_name":"Eve","last_name":"Holt","avatar":"https://s3.amazonaws.com/uifaces/faces/twitter/marcoramires/128.jpg"},{"id":5,"first_name":"Charles","last_name":"Morris","avatar":"https://s3.amazonaws.com/uifaces/faces/twitter/stephenmoon/128.jpg"},{"id":6,"first_name":"Tracey","last_name":"Ramos","avatar":"https://s3.amazonaws.com/uifaces/faces/twitter/bigmancho/128.jpg"}]};

//myJsonObj = JSON.parse(TextObj);
//console.log("my JSON OBJ: ", myJsonObj);


for(x in myJsonObj.data){
    if(myJsonObj.data[x].avatar.includes("https")){
        console.log("user exist: ", myJsonObj.data[x].first_name);
    }else{
        console.log("user does not exist!!");
    }
}

TextObj = JSON.stringify(myJsonObj);
console.log(TextObj);

setnwa35nw2345

node

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