Node.js:Buffers in node.js

 create buffer from string

var buf = Buffer.from('abc');

console.log(buf.toString());

create empty buffer of length 15

var buf = Buffer.alloc(15);

console.log(buf);

return size of buffer

var buf = Buffer.from('abc');

console.log(buf.length);

join three buffer object to one

var buf1 = Buffer.from('a');

var buf2 = Buffer.from('b');

var buf3 = Buffer.from('c');

var arr = [buf1, buf2, buf3];

var buf = Buffer.concat(arr);

console.log(buf.toString());

A Buffer cannot be resized.

Max Buffer size :

var buffer = require('buffer')

console.log(buffer.constants.MAX_LENGTH)

it is less on 32 bit machine & more on 64 bit machines.

Checking wheather object is buffer

var buf1 = Buffer.from('a');

var buf2 = "sa"

console.log(Buffer.isBuffer(buf1));

console.log(Buffer.isBuffer(buf2));

Return the number of bytes in the string "abc":

var len3 = Buffer.byteLength('abc');

console.log(len3);

Check the length of a buffer object:

var buf = Buffer.alloc(15);

var len1 = Buffer.byteLength(buf);

var len2 = buf.length;

console.log(len1);

console.log(len2);

return index from where the searched value is starting. It returns -1 if the value is not present in the buffer.

const buffer = Buffer.from('GeeksforGeeks: A computer science portal');

const output = buffer.indexOf('computer');

console.log(output);

output:

17

const buffer = Buffer.from('geeks community');

const output = buffer.indexOf(101);

const output1 = buffer.indexOf('geeks community');

const output2 = buffer.indexOf('com',7);//start searching at position 7 starting from 0

console.log(output);

console.log(output1);

console.log(output2);

output:

0

1

-1

check if two buffers are equal

var buf1 = Buffer.from('Hi');

var buf2 = Buffer.from('Hi');

console.log(buf1.equals(buf2));

output:

true

subarray:

const buf = Buffer.from('GeeksforGeeks', 'ascii');

console.log("Original buffer is: " + buf);

cropped_buf = buf.subarray(5, 10);

console.log("Cropped buffer is: " + cropped_buf);

cropped_buf[0] = 70; // F

cropped_buf[1] = 79; // O

cropped_buf[2] = 82; // R

console.log("Cropped buffer after modification is: " + cropped_buf);

console.log("Original buffer after modification is: " + buf);

output:

Original buffer is: GeeksforGeeks

Cropped buffer is: forGe

Cropped buffer after modification is: FORGe

Original buffer after modification is: GeeksFORGeeks

another example with negative index

const buf = Buffer.from('GeeksforGeeks', 'ascii');

console.log("Original buffer is: " + buf);

cropped_buf = buf.subarray(-12, -1);

console.log("Cropped buffer is:" + cropped_buf);

cropped_buf = buf.subarray(-10, -5);

console.log("Cropped buffer is: " + cropped_buf);

cropped_buf = buf.subarray();

console.log("Cropped buffer is: " + cropped_buf);

output:

Original buffer is: GeeksforGeeks

Cropped buffer is:eeksforGeek

Cropped buffer is: ksfor

Cropped buffer is: GeeksforGeeks

include or not

const buffer = Buffer.from('Geek One');

console.log(buffer.includes('Geek'));

output:

true

another example

const buffer = Buffer.from('GeeksforGeeks: A computer science portal');

const output = buffer.includes('Geek', 15);

console.log(output);

output:

false

copy method:

let buffer2 = Buffer.from('for');

let buffer1 = Buffer.from('GeeksandGeeks');

buffer2.copy(buffer1, 5,0)

console.log(buffer1.toString());

output:

GeeksforGeeks

compare:

return 0,-1 or 1

const buffer1 = Buffer.from('Geek');

const buffer2 = Buffer.from('Geek');

const op = Buffer.compare(buffer1, buffer2);

console.log(op);

output:

0

sort buffer array:

const buffers = [

Buffer.from('A', 'utf8'),

Buffer.from('C', 'utf8'),

Buffer.from('B', 'utf8')

];

buffers.sort(Buffer.compare);

compare on buffer object

const buffer1 = Buffer.from('GeeksOne');

const buffer2 = Buffer.from('GeekTwo');

let op = buffer1.compare(buffer2, 4);

let op1 = buffer1.compare(buffer2, 0, 7, 5);

console.log(op);

console.log(op1);

output:

-1

1

another example:

const buffer1 = Buffer.from("Geeks");

const buffer2 = Buffer.from("GeeksFor");

let op1 = buffer1.compare(buffer2, 0, 5);

console.log(op1);

output:

0