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Javascript – read from file in node js usign terminal error

When i want to read a file in node js it won’t display the file in the browser when I execute. and in the terminal says no such file or directory while I use the exact file path anyone can answer this why?

hwo to do sos uisng termianl

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3

Answers


  1. Chosen as BEST ANSWER
    0 
    const fs = require('fs');
const events = require('events');
const bf =require('buffer');

const REQUIRED_LINES = 10;  

function createWatcher(logFile) {
  const queue = [];
  const eventEmitter = new events.EventEmitter();
  const buffer = Buffer.alloc(bf.constants.MAX_STRING_LENGTH); 

  function readfile(curr, prev) {
    // Create a read stream from the file
    const readStream = fs.createReadStream(logFile, {
        start: prev.size,
        encoding: 'utf8'
    });

    let data = '';

    readStream.on('data', chunk => {
        data += chunk;
    });

    readStream.on('end', () => {
        let logs = data.split('n').slice(1);
        console.log("logs read: " + logs);

        if (logs.length >= REQUIRED_LINES) {
            logs.slice(-REQUIRED_LINES).forEach(elem => queue.push(elem));
        } else {
            logs.forEach(elem => {
                if (queue.length === REQUIRED_LINES) {
                    console.log("queue is full");
                    queue.shift();
                }
                queue.push(elem);
            });
        }
        eventEmitter.emit("process", logs);
    });

    readStream.on('error', err => {
        console.error("Error reading the file:", err);
    });
  }

    // Define the start function
  function startpoint() {
      fs.open(logFile, 'r', (err, fd) => {
        if (err) throw err;

        let data = '';
        let logs = [];
        
        fs.read(fd, buffer, 0, buffer.length, 0, (err, readbytes) => {
          if (err) throw err;

          if (readbytes > 0) {
            data = buffer.slice(0, readbytes).toString();
            logs = data.split("n");
            queue.length = 0;  // Clear the queue
            logs.slice(-REQUIRED_LINES).forEach((elem) => queue.push(elem));
          }

          fs.close(fd, (err) => {
            if (err) throw err;
          });
        });

        fs.watchFile(logFile, { interval: 1000 }, (curr, prev) => {
          readfile(curr, prev);
        });
      });
  }

  return {
    getLogs: function() {
      return queue;
    },
    emit: function(eventName, ...args) {
      eventEmitter.emit(eventName, ...args);
    },

    on: function(eventName, listener) {
      eventEmitter.on(eventName, listener);
    },
    off: function(eventName, listener) {
      eventEmitter.off(eventName, listener);
    },

    start: startpoint
  };
}
module.exports = createWatcher;

  2. 0 
    const fs = require('fs');
const path = 'test.log'; 

let lineNumber = 1; // Initialize line number

const getRandomInt = (min, max) => Math.floor(Math.random() * (max - min + 1)) + min;

// Function to generate a random string of characters
const generateRandomString = (length) => {
  const characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
  let result = '';
  for (let i = 0; i < length; i++) {
    result += characters.charAt(getRandomInt(0, characters.length - 1));
  }
  return result;
};

// Function to write a new line to the file
const writeToFile = () => {
  const randomString = generateRandomString(8); // Generate an 8-character long random string
  const content = `Line ${lineNumber}: ${randomString}`;

  // Append a newline before the new content to ensure it starts on a new line
  fs.appendFile(path, `n${content}`, 'utf8', (err) => {
    if (err) {
      console.error('Error appending to file:', err);
      return;
    }
    console.log(`Content successfully appended: ${content}`);

    // Increment line number
    lineNumber++;
  });
};

// Interval in milliseconds (e.g., 2000 ms = 2 seconds)
const interval = 1000;

// Run the write function continuously
setInterval(writeToFile, interval);
<!DOCTYPE html>
<html>
   <head><title>Tail -f</title></head>
   <script src="/socket.io/socket.io.js"></script>
   <script>
      var socket = io("ws://localhost:3000");
      socket.on('update-log', function(data){
          console.log(data);
          for(elem of data) document.getElementById('message-container').innerHTML +='<p>' + elem + '</br><p>';
      });
      socket.on('init',function(data){
        console.log(data);
        for(elem of data) document.getElementById('message-container').innerHTML +='<p>' + elem + '</br><p>';      })
   </script>
   <body>
       <h1>Log monitoring app</h1>
      <div id="message-container"></div>
      </body>
   </html>const express = require('express');
const app = express();
const http = require('http').Server(app);
const io = require('socket.io')(http);
const path = require('path'); 
const Watcher = require('./watch2');
 
let watcher = new Watcher("test.log");

watcher.start();


app.get('/log', (req, res) => {
    console.log("request received");
    var options = {
        root: path.join(__dirname)
    };
     
    var fileName = 'index.html';
    res.sendFile(fileName, options, function (err) {
        if (err) {
            next(err);
        } else {
            console.log('Sent:', fileName);
        }
    });
})

io.on('connection', function(socket){
   // console.log(socket);
    console.log("new connection established:"+socket.id);

      watcher.on("process", function process(data) {
        socket.emit("update-log",data);
      });
      
      let data = watcher.getLogs();
      socket.emit("init",data);
   });

http.listen(3000, function(){
    console.log('listening on localhost:3000');
});
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  3. 0 
    const express = require('express');
const { exec } = require('child_process');
const app = express();
const port = 3000;

// Define browser commands and paths
const browserPaths = {
  chrome: {
    start: 'google-chrome', // Use 'google-chrome-stable' if installed
    stop: 'pkill chrome',
    cleanup: 'sudo rm -rf ~/.config/google-chrome/Default/*'
  },
  firefox: {
    start: 'firefox', // Use 'firefox' command
    stop: 'pkill firefox',
    cleanup: 'sudo rm -rf ~/.mozilla/firefox/*.default-release/'
  }
};

// Root route
app.get('/', (req, res) => {
  res.send('Welcome to the Browser Service API. Use /start, /stop, /cleanup, or /geturl.');
});

// Start a browser with a specific URL
app.get('/start', (req, res) => {
  const { browser, url } = req.query;

  if (!browserPaths[browser] || !url) {
    return res.status(400).send('Invalid parameters');
  }

  const startCommand = `${browserPaths[browser].start} ${url}`;

  exec(startCommand, (error) => {
    if (error) {
      return res.status(500).send('Failed to start browser');
    }
    res.send('Browser started');
  });
});

// Stop a browser
app.get('/stop', (req, res) => {
  const { browser } = req.query;

  if (!browserPaths[browser]) {
    return res.status(400).send('Invalid browser');
  }

  exec(browserPaths[browser].stop, (error) => {
    if (error) {
      return res.status(500).send('Failed to stop browser');
    }
    res.send('Browser stopped');
  });
});

// Clean up browsing data
app.get('/cleanup', (req, res) => {
  const { browser } = req.query;

  if (!browserPaths[browser]) {
    return res.status(400).send('Invalid browser');
  }

  exec(browserPaths[browser].cleanup, (error) => {
    if (error) {
      return res.status(500).send('Failed to clean up browser');
    }
    res.send('Browser cleaned up');
  });
});

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