1. module line-reader
   1. function line-reader.eachLine (filename, options, iteratee, cb)
   2. function line-reader.open (filenameOrStream, options, cb)

module line-reader

function line-reader.eachLine (filename, options, iteratee, cb)

• description and source-code

  function eachLine(filename, options, iteratee, cb) {
    if (options instanceof Function) {
      cb = iteratee;
      iteratee = options;
      options = undefined;
    }
    var asyncIteratee = iteratee.length === 3;
  
    var theReader;
    var getReaderCb;
  
    open(filename, options, function(err, reader) {
      theReader = reader;
      if (getReaderCb) {
        getReaderCb(reader);
      }
  
      if (err) {
        if (cb) cb(err);
        return;
      }
  
      function finish(err) {
        reader.close(function(err2) {
          if (cb) cb(err || err2);
        });
      }
  
      function newRead() {
        if (reader.hasNextLine()) {
          setImmediate(readNext);
        } else {
          finish();
        }
      }
  
      function continueCb(continueReading) {
        if (continueReading !== false) {
          newRead();
        } else {
          finish();
        }
      }
  
      function readNext() {
        reader.nextLine(function(err, line) {
          if (err) {
            finish(err);
          }
  
          var last = !reader.hasNextLine();
  
          if (asyncIteratee) {
            iteratee(line, last, continueCb);
          } else {
            if (iteratee(line, last) !== false) {
              newRead();
            } else {
              finish();
            }
          }
        });
      }
  
      newRead();
    });
  
    // this hook is only for the sake of testing; if you choose to use it,
    // please don't file any issues (unless you can also reproduce them without
    // using this).
    return {
      getReader: function(cb) {
        if (theReader) {
          cb(theReader);
        } else {
          getReaderCb = cb;
        }
      }
    };
  }

• example usage

  ...
  The `eachLine` function reads each line of the given file.  Upon each new line,
  the given callback function is called with two parameters: the line read and a
  boolean value specifying whether the line read was the last line of the file.
  If the callback returns `false`, reading will stop and the file will be closed.
  
  var lineReader = require('line-reader');
  
  lineReader.eachLine('file.txt', function(line, last) {
    console.log(line);
  
    if (/* done */) {
      return false; // stop reading
    }
  });
  ...

function line-reader.open (filenameOrStream, options, cb)

• description and source-code

  function open(filenameOrStream, options, cb) {
    if (options instanceof Function) {
      cb = options;
      options = undefined;
    }
  
    var readStream;
  
    if (typeof filenameOrStream.read == 'function') {
      readStream = filenameOrStream;
    } else if (typeof filenameOrStream === 'string' || filenameOrStream instanceof String) {
      readStream = fs.createReadStream(filenameOrStream);
    } else {
      cb(new Error('Invalid file argument for LineReader.open.  Must be filename or stream.'));
      return;
    }
  
    readStream.pause();
    createLineReader(readStream, options, cb);
  }

• example usage

  ...
    console.log("I'm done!!");
  });
  
  For more granular control, `open`, `hasNextLine`, and `nextLine` maybe be used
  to iterate a file (but you must `close` it yourself):
  
  // or read line by line:
  lineReader.open('file.txt', function(err, reader) {
    if (err) throw err;
    if (reader.hasNextLine()) {
      reader.nextLine(function(err, line) {
        try {
          if (err) throw err;
          console.log(line);
        } finally {
  ...