Array

ArrayBuffer: ArrayBuffer object is used to represent a generic raw binary data buffer. You can think of as contiguous memory buffer of the fixed length. You can refer it as a “byte array”, but you can’t directly modify it, instead you have to create view on top it using typed arrays like Uint8Array, Int16Array, Uint32Array,… etc.

// You can run below code inside node REPL
 
// create an array buffer of 8 bytes
const buffer = new ArrayBuffer(8)
// buffer
// ArrayBuffer {
//   [Uint8Contents]: <00 00 00 00 00 00 00 00>,
//   byteLength: 8
// }
 
const ua8 = new Uint8Array(buffer)
const a8 = new Int8Array(buffer)
const a16 = new Int16Array(buffer)
 
ua8[0] = 255
ua8[1] = 255
 
console.log(a16[0])
// above will print `-1`. You can brainstorm it. Hint: Two's Complement and the bytes we are changing.

There is nothing new here, you can create this same buffers in any other language like for example in c you can use malloc

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
 
void print_raw_buffer(void *buffer, size_t size);
 
int main()
{
    void *buffer = malloc(8);
 
    uint8_t *ua8 = buffer;
    const int8_t *a8 = buffer;
    const int16_t *a16 = buffer;
 
    ua8[0] = 255;
    ua8[1] = 255;
 
    print_raw_buffer(buffer, sizeof(buffer)); // ff ff 00 00 00 00 00 00
 
    printf("%d\n", a16[0]); // -1
    free(buffer);
    return 0;
}
 
void print_raw_buffer(void *buffer, size_t size)
{
    uint8_t *u8 = buffer;
    for (size_t i = 0; i < size; i++)
    {
        printf("%02x ", u8[i]);
    }
    printf("\n");
}