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Hands on node by Pedro Teixeira exercises. These are the Buffer exercises the first set. Emitters the second.
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/* | |
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)); | |
} | |
}); | |
}); |
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