buffer (Binary data storage module)

Used to handle raw binary data (can be text in utf8 or jpeg or anything), heavily used when working with files and receiving data from <input type="file">.

Please keep in mind, as of 21 century, most text files are utf8 encoded, while String objects in javascript are internally stored in utf-16, hence conversion is needed while working with files, writting data to stdout or anything else.

Usage:

var buffer=require("buffer");

Working with buffer:

var buffer=require("buffer");
var fs=require("fs");

// Reading contents of /etc/passwd and storing it as a String
var f2=new fs.File("/etc/passwd");
f2.open("r");
var contents=f2.read().toString("utf-8");
f2.close();

// Creating Buffer object filled with zeroes (100 bytes)
var zeroes100=new buffer.Buffer(100,0);
var f3=new fs.File("/tmp/zeroes-100.bin");
f3.open("w");
f3.write(zeroes100);
f3.close();

// Filling zeroes100 object with bytes 0..99
for (var i=0;i<zeroes100.length;i++) zeroes100[i]=i;

// Creating a new Buffer object containing a part of zeroes100 object data
var part=zeroes100.slice(20,40);
// contains bytes [20,21 .... 39]
var f3=new fs.File("/tmp/filled-20-39.bin");
f3.open("w");
f3.write(part);
f3.close();

Accepting <input type="file"> from http request:

var fs=require("fs");

// <input type="file" name="myjpeg">
var data=request.post.files.myjpeg.data;
var f1=new fs.File("/tmp/myfile.jpg");
f1.open("w");
f1.write(data);
f1.close();

List of methods of Buffer class

Name	Arguments	Returns	Description
new	Buffer src		Creates an object of Buffer class, copying data from another Buffer.
new	int length		Creates an object of Buffer class, size length bytes, filled with 0
new	int length, int fill		Creates an object of Buffer class, size length bytes, filled with fill (byte).
new	String src		Creates an object of Buffer class, with src converted to utf-8 encoding.
toString	String enc	String	Returns Strings, converted from encoding enc. Throws exception if cannot convert from encoding.
range	int first, int last	Buffer	Returns an object of Buffer class, copied from byte first to byte last (not including). Throws exception if indexes are incorrect.
slice			same (deprecated?)
fill	int fill, int first, int last		Fills a part of binary data with fill (byte).
copy	Array dst, int off_t, int off_s, int len
copy	Buffer dst, int off_t, int off_s, int len
copyFrom	Array src, int off_s, int off_t, int len
copyFrom	Buffer src, int off_s, int off_t, int len
read			Not implemented yet
write			Not implemented yet

List of properties of Buffer class

Name	Arguments	Returns	Description
length		int	Returns buffer size, in bytes.
[]	int pos	int	Getter, Setter for byte value at position pos