Buffer: AN area of memory (outside the V8 heap memory) dedicated to temporary data, containing a specified number of bytes or characters. As opposed to strings, buffers are particularly useful for storing binary data.

An instance of the Buffer type is similar to an array of integers ranging from 0 to 255, where each element is a one-byte hexadecimal integer; Once created, it cannot be resized. Unlike a String, any part of a Buffer can be modified.

The Buffer class is a member of the global object, so use this module without requiring (‘ Buffer ‘).

Creating a Buffer instance

An instance of a Buffer object, which can be obtained by reading a file or constructed directly:

// Create a Buffer of length 10 filled with zero.
const buf1 = Buffer.alloc(10);

// Create a Buffer of length 10 filled with 0x1.
const buf2 = Buffer.alloc(10.1);

// Create an uninitialized Buffer of length 10.
// This method is faster than calling buffer.alloc (),
// However, the returned Buffer instance may contain old data,
// Therefore you need to rewrite it with fill() or write().
const buf3 = Buffer.allocUnsafe(10);

// Create a three-byte buffer of 0x01, 0x0A, 0xFF
const buf4=Buffer.from([1.10.255]);

// Create a 4-byte buffer of 0x61,0x62,0x41,0x42
const buf5=Buffer.from('abAB');

// Create a 6-byte buffer of 0xe4, 0xB8,0xe4,0xba, 0x8C
const buf6=Buffer.from('一二'.'utf8');
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In versions of Node.js prior to 6.0.0, Buffer instances were created using the Buffer constructor. Various forms of the new Buffer() constructor have been deprecated in order to make Buffer instance creation more reliable and less error-prone. Instead, use separate buffer.from (), buffer.alloc (), and buffer.allocunsafe () methods.

Node.js currently supports the following character encodings:

var s1='AA';
var s2='BB';
var s3='CC';
var buf1=Buffer.alloc(6);
buf1.write(s1);
buf1.write(s2,2);
buf1.write(s3,4);
console.log(buf1);
console.log(buf1.toString());
//<Buffer 41 41 42 42 43 43>
//AABBCC
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console.log(buf.toString());				// The default encoding is UTF-8
console.log(buf.toString('binary'));
console.log(buf.toString('hex'));
console.log(buf.toString('ascii'));
console.log(buf.toString('utf8'));
console.log(buf.toString('utf16le'));
console.log(buf.toString('base64'));
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Traverse the Buffer

You can use a for loop with buf.length and buf[index] to iterate over each data in the buffer, or you can use the new ES6 feature for… The of loop iterates through each data value.

// Create a buffer of 8 bytes
const buf=Buffer.from('ab one');
// Use the for loop to iterate through the buffer
for(var i=0; i<buf.length; i++){console.log('%d-%s',buf[i],buf[i].toString(16))}/ / used for... Of traverses the buffer
for(var v of buf){
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const buf1=Buffer.from('ABC');
const buf2=Buffer.from('One, two, three');
var buf3=Buffer.alloc(buf1.length+buf2.length);// Create a buffer of the specified length
buf1.copy(buf3);// Copy buF1 buffer data to BUF3 with default offset starting at 0
buf2.copy(buf3,buf1.length);// Copy the buF2 buffer data to BUF3 with the offset at the end of buf1
console.log(buf3.toString());
/ / ABC in 123
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const buf1=Buffer.from('ABC');
console.log(buf1);

var sub=buf1.slice(2);
console.log(sub);

sub[0] =0x44;
console.log(sub);
console.log(buf1)
//<Buffer 41 42 43>
//<Buffer 43>
//<Buffer 44>
//<Buffer 41 42 44>
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