Hands on node by Pedro Teixeira exercises. These are the Buffer exercises the first set. Emitters the second.

HandsOnNode

/*
Buffers
Exercise 1
Create buffer 100 bytes
ill it with 0 to 99
*/

var buffer1 = new Buffer(100);

for(var i=0; i<buffer1.length;i++){
	buffer1[i]=i;
}

console.log(buffer1);

/*
Exercise 2
Create buffer 100 bytes
ill it with 0 to 99
then slice buffer with bytes 40 t0 60
*/

var buffer1 = new Buffer(100);

for(var i=0; i<buffer1.length;i++){
	buffer1[i]=i;
}

var buffer2 = new Buffer(20);

buffer2 = buffer1.slice(40,60);

console.log(buffer1);
console.log(buffer2);


/*
Buffers
Exercise 3
Create buffer 100 bytes
ill it with 0 to 99
then create new buffer and copy bytes 
40 to 60 of first beffer into it
*/

var buffer1 = new Buffer(100);
var buffer2 = new Buffer(20);

for(var i=0; i<buffer1.length;i++){
	buffer1[i]=i;
}

buffer1.copy(buffer2, 0, 40,60);

console.log(buffer2);

/*
Emitters
Exercise 1
Build a pseudo-class named “Ticker” that emits a “tick” event every 1 second.

*/

var EventEmitter=require('events').EventEmitter, util = require('util');
//HereistheMyClassconstructor:
var Ticker=function(){ 
	var self = this;
	setInterval(function() {
    self.emit("tick");
    console.log('tick');
  }, 1000);
};
util.inherits(Ticker,EventEmitter);

var tick = new Ticker();

/*
Emmiters
Exercise 2
Build a script that instantiates one Ticker and bind to the “tick” event, printing “TICK” every time it gets one.
*/

var EventEmitter=require('events').EventEmitter, util = require('util');
//HereistheMyClassconstructor:
var Ticker=function(){ 
	var self = this;
	setInterval(function() {
    self.emit("tick");
   // console.log('tick');
  }, 1000);
};
util.inherits(Ticker,EventEmitter);

var tick = new Ticker();
tick.on('tick',function(){
  console.log('TICK');
});

/*
File System
Exercise 1
Having a file named a.txt, print the size of that files in bytes.
*/


var fs=require('fs');
fs.stat(__dirname+'/a.txt',function(err,stats){
 if (err) {
 console.log(err.message);
  return;
}
 console.log(stats.size);
 });
 
 /*
File System
Exercise 2
Having a file named a.txt, print bytes 10 to 14.

*/


var fs=require('fs');
fs.open(__dirname+'/a.txt','r',function(err,fd){
	if (err) throw err;
var readBuffer = new Buffer(1024),
    bufferOffset = 0,
    bufferLength = 4;
    filePosition = 10;
fs.read(fd, readBuffer, bufferOffset, bufferLength, filePosition, function(err, readBytes) {
	if (err) throw err;
	console.log('just read ' + readBytes + ' bytes'); if (readBytes > 0) {
        console.log(readBuffer.slice(0, readBytes));
      }
	}); 
});