CODEWITHSUNDEEP
javascriptlinuxnode.js
Sage Hopkins
Sage Hopkins

Reputation: 183

NodeJS - Reading Line By Line Function + While Loop

I am currently have an issue where I am trying to read a file line by line and then output the contents of said file onto the webpage hosted by nodejs. I am trying to use a while loop, but Im not sure its working, and I don't really know what otherway to go about it. I could use some help. 

var sys = require('util');
var exec = require('child_process').exec; 
//Find Audio Files in Audio Directory
exec("~/music_Controller/./music_Find.sh");

var contents = '';

var fs = require('fs');

//Reads file defined on input (readLines(input, func);) and reads them line by line
function readLines(input, func) {
  var remaining = '';

  input.on('data', function(data) {
    remaining += data;
    var index = remaining.indexOf('\n');
    while (index > -1) {
      var line = remaining.substring(0, index);
      remaining = remaining.substring(index + 1);
      func(line);
      index = remaining.indexOf('\n');
    }
  });

  input.on('end', function() {
    if (remaining.length > 0) {
      func(remaining);
    }
  });
}

function func(data) {
  contents = data;
}




readLines(input, func);



function puts(error, stdout, stderr) { sys.puts(stdout) }

var http = require('http');
var server = http.createServer(function(request, response) {
	var input = fs.createReadStream('/root/music_Controller/songs.txt');
  while(readLines(input, func)){
  	response.write(contents);

  }

  response.writeHead(200, {"Content-Type": "text/html"});
  response.write("<!DOCTYPE html>");
  response.write("<html>");
  response.write("<head>");
  response.write("<title>Hello World Page</title>");
  response.write("</head>");
  response.write("<body>");
  response.write("Hello World!");
  response.write("</body>");
  response.write("</html>");
  response.end();

  //Execute Shell Script/Command
  exec("play ~/music_Controller/song.mp3", puts);
  console.log("exec");
});

server.listen(8911);
console.log("Server is listening");

Thanks, Sage

Upvotes: 0

Views: 1600

Answers (1)

Zeeshan Hassan Memon
Zeeshan Hassan Memon

Reputation: 8325

Following options let you Either read whole file accumulate results and send as a one response to web-page Or if you have web-socket open or other form of connection with client you can send earch line that is read and processed if needed.

Option 1:

Tail = require('tail').Tail;

tail = new Tail("/root/music_Controller/songs.txt", "\n", {}, true);

tail.on("line", function(data) {
  console.log(data);
});

tail.on("error", function(error) {
  console.log('ERROR: ', error);
});

Option 2: npm install linebyline

var readline = require('linebyline'),
rl = readline('./somefile.txt');
rl.on('line', function(line, lineCount, byteCount) {
     // do something with the line of text 
})
.on('error', function(e) {
    // something went wrong 
 });

For complete working solution get this Github Repo and run line_by_line.js

Happy Helping!

Upvotes: 3

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