Dynamic-buffer NPM

Dynamic Buffer for Node.js

An automatically resizing storage size buffer type for Node.js that is based on Node.js builtin Buffer.

Installation

You can install this library by npm with the following command:

npm install dynamic-buffer

You can also install by yarn or other npm alternative package managers:

yarn add dynamic-buffer

Getting Started

Imports DynamicBuffer from dynamic-buffer package:

import { DynamicBuffer } from 'dynamic-buffer';

Creates DynamicBuffer instance with default initial size or the specific size:
```
const buffer = new DynamicBuffer();
```

Appends data into buffer:

buffer.append('Hello ');
buffer.append('world!');

Exports data to string or builtin buffer object without unused bytes:

console.log(buffer.length);
// 12
const buf = buffer.toBuffer();
console.log(buf.toString());
// Hello world!
const str = buffer.toString();
console.log(str);
// Hello world!

Usages

Write Data

You can write a string into a buffer by append method, it'll add the string to the end of the buffer:

buf.append('Hello');
buf.append(' ');
buf.append('world');
console.log(buf.toString());
// Hello world

And you can also set the string length to write. Like the second line of the following example, it'll write 'Script!' into buffer and without the last two '!' symbols:

buf.append('Java');
buf.append('Script!!!', 7);
console.log(buf.toString());
// JavaScript!

You can also use write method to write data to the specified position in the buffer:

buf.append('Hello world!');
buf.write('Node.js', 6);
console.log(buf.toString());
// Hello Node.js

Read Data

You can access the byte at the specified position in the buffer by read or at methods:

const buf = new DynamicBuffer('Hello world');

buf.at(0); // 72
buf.read(1); // 101

Iteration

DynamicBuffer provides three ways to iterate data from the specified buffer, you can use them with for...of statement.

entries() returns an iterator of key-value pair (index and byte) from the buffer.

buf.append('Hello');
for (const pair of buf.entries()) {
  console.log(pair);
}
// [ 0, 72 ]
// [ 1, 101 ]
// [ 2, 108 ]
// [ 3, 108 ]
// [ 4, 111 ]

values() returns an iterator of data(byte) from the buffer.

buf.append('Hello');
for (const value of buf.values()) {
  console.log(value);
}
// 72
// 101
// 108
// 108
// 111

keys() returns an iterator of buffer keys (indices).

Search

You can search a value in the buffer by indexOf or lastIndexOf, and get the position of the first/last occurrence in the buffer. The searching value can be a string, a number, a Buffer, an Uint8Array, or another DynamicBuffer.

buf.append('ABCABCABC');
buf.indexOf('ABC'); // 0
buf.lastIndexOf('ABC'); // 6
buf.indexOf('abc'); // -1

Comparison

You can compare DynamicBuffer object with another DynamicBuffer object, Node.js builtin Buffer object, or an Uint8Array by compare or equals methods.

For compare method, it returns a number to indicate whether the buffer comes before, after, or is the same as another buffer in sort order.

buf.append('ABC');
console.log(buf.compare(Buffer.from('ABC')));
// 0
console.log(buf.compare(Buffer.from('BCD')));
// -1

For equals method, it returns a boolean value to indicate whether the buffer is the same as the target buffer.

buf.append('ABC');
console.log(buf.equals(Buffer.from('ABC')));
// true
console.log(buf.equals(Buffer.from('BCD')));
// false

Export Data

You can export buffer content (without unused parts) to string, Buffer object, or JSON representation object.

buf.append('Hello');
console.log(buf.toString());
// Hello
const dataBuffer = buf.toBuffer();
console.log(buf.length, dataBuffer.toString());
// 5 Hello
console.log(JSON.stringify(buf)); // JSON.stringify implicitly calls toJSON method.
// {"type":"Buffer","data":[72,101,108,108,111]}

For toString and toBuffer methods, you can also set the start and end offsets to export the subset of written data.

buf.append('Hello world!!!');
console.log(buf.toString('utf8', 6, 11));
// world

Utils

We provided isDynamicBuffer function to indicating an object is a DynamicBuffer object or not.

import { isDynamicBuffer } from 'dynamic-buffer';

const buf1 = Buffer.alloc(8);
const buf2 = new DynamicBuffer();

isDynamicBuffer(buf1); // false
isDynamicBuffer(buf2); // true