having-fun-coding · May 18, 2015 21:51
diff --git a/readMe.txt b/readMe.txt
 Write a program that uses a single asynchronous filesystem operation to read a file and print the number of newlines it contains to the console (stdout), similar to running cat file | wc -l.

 The full path to the file to read will be provided as the first command-line argument.

 -------------------------------------------------------------------------------

 # HINTS

 The solution to this problem is almost the same as the previous problem except you must now do it the Node.js way: asynchronous.

 Instead of fs.readFileSync() you will want to use fs.readFile() and instead of using the return value of this method you need to collect the value from a callback function that you pass in as the second argument. To learn more about callbacks, check out: [https://github.com/maxogden/art-of-node#callbacks](https://github.com/maxogden/art-of-node#callbacks).

 Remember that idiomatic Node.js callbacks normally have the signature:

    function callback (err, data) { /* ... */ }

 so you can check if an error occurred by checking whether the first argument is truthy. If there is no error, you should have your Buffer object as the second argument. As with readFileSync(), you can supply 'utf8' as the second argument and put the callback as the third argument and you will get a String instead of a Buffer.
diff --git a/gistfile1.txt b/gistfile1.txt
 var fs = require('fs');
 var path = process.argv[2];

 fs.readFile(path, 'utf8', function(err,data) {
  var lines = data.split('\n');
  console.log(lines.length-1);
 });
	Write a program that uses a single asynchronous filesystem operation to read a file and print the number of newlines it contains to the console (stdout), similar to running cat file \| wc -l.

	The full path to the file to read will be provided as the first command-line argument.

	-------------------------------------------------------------------------------

	# HINTS

	The solution to this problem is almost the same as the previous problem except you must now do it the Node.js way: asynchronous.

	Instead of fs.readFileSync() you will want to use fs.readFile() and instead of using the return value of this method you need to collect the value from a callback function that you pass in as the second argument. To learn more about callbacks, check out: [https://github.com/maxogden/art-of-node#callbacks](https://github.com/maxogden/art-of-node#callbacks).

	Remember that idiomatic Node.js callbacks normally have the signature:

	function callback (err, data) { /* ... */ }

	so you can check if an error occurred by checking whether the first argument is truthy. If there is no error, you should have your Buffer object as the second argument. As with readFileSync(), you can supply 'utf8' as the second argument and put the callback as the third argument and you will get a String instead of a Buffer.
	var fs = require('fs');
	var path = process.argv[2];

	fs.readFile(path, 'utf8', function(err,data) {
	var lines = data.split('\n');
	console.log(lines.length-1);
	});