varint

What is varint?

The varint npm package is used for encoding and decoding variable-length integers. It is particularly useful in scenarios where you need to efficiently store or transmit integers that can vary greatly in size, such as in network protocols or file formats.

What are varint's main functionalities?

Encoding Integers

This feature allows you to encode an integer into a variable-length format. The encoded result is an array of bytes.

const varint = require('varint');
const encoded = varint.encode(300); // [172, 2]
console.log(encoded);

Decoding Integers

This feature allows you to decode a variable-length encoded integer back into its original integer form.

const varint = require('varint');
const decoded = varint.decode([172, 2]); // 300
console.log(decoded);

Encoding Integers to Buffer

This feature allows you to encode an integer directly into a Buffer, which can be useful for more advanced use cases involving binary data.

const varint = require('varint');
const buffer = Buffer.alloc(10);
const bytesWritten = varint.encode(300, buffer, 0); // 2
console.log(buffer.slice(0, bytesWritten));

Decoding Integers from Buffer

This feature allows you to decode an integer from a Buffer, which is useful when working with binary data streams.

const varint = require('varint');
const buffer = Buffer.from([172, 2]);
const decoded = varint.decode(buffer); // 300
console.log(decoded);

Other packages similar to varint

protobufjs

protobufjs is a comprehensive library for working with Protocol Buffers, which includes functionality for encoding and decoding variable-length integers. It is more feature-rich compared to varint, offering schema definitions and more complex data structures.

msgpack-lite

msgpack-lite is a library for encoding and decoding data in the MessagePack format, which includes support for variable-length integers. It is similar to varint but also supports a wider range of data types and is optimized for performance.

leb128

leb128 is a library for encoding and decoding LEB128 (Little Endian Base 128) integers, which is another form of variable-length integer encoding. It is similar to varint but uses a different encoding scheme.

README

varint

decode protobuf-style varint bytes and emit whole integers when enough have been accumulated that a number can be constructed; also encode whole numbers to an array of varint style bytes.

var varint = require('varint')

var bytes = varint.encode(300) // === [0xAC, 0x02]
  , vi = varint()

vi.once('data', function(num) {
  console.log('got', num)
})

vi.write(bytes[0])
vi.write(bytes[1]) // "got 300"

api

varint = require('varint')

varint.encode(num[, output=[], offset=0]) -> array

encodes num into either the array given by offset or a new array at offset and returns that array.

vi = varint() -> EventEmitter

return a new varint instance.

vi.write(byte) -> undefined

write a byte to the varint. if the byte is "final" (i.e., does not have the bit at 0x80 set), it will attempt to compile the number and emit it as a data event.

License

MIT