node-int64

What is node-int64?

The node-int64 npm package is used for handling 64-bit integer values in Node.js. It provides functionality to represent, manipulate, and convert 64-bit integers, which are not natively supported in JavaScript due to its use of IEEE 754 floating-point numbers for all numeric values.

What are node-int64's main functionalities?

Creating 64-bit integers

This feature allows the creation of 64-bit integer instances from various inputs such as number, string, or buffer.

const Int64 = require('node-int64');
const int64 = new Int64('0x1234567890abcdef');

Reading 64-bit integers from buffers

This feature enables reading 64-bit integers directly from buffers, which is useful when dealing with binary data streams.

const Int64 = require('node-int64');
const buffer = Buffer.from('1234567890abcdef', 'hex');
const int64 = new Int64(buffer);

Converting 64-bit integers to strings

This feature allows the conversion of 64-bit integers to their string representation, which can be displayed or stored as text.

const Int64 = require('node-int64');
const int64 = new Int64('0x1234567890abcdef');
const str = int64.toString();

Converting 64-bit integers to native JavaScript numbers

This feature provides the ability to convert 64-bit integers to native JavaScript numbers, with the caveat that precision might be lost for large values.

const Int64 = require('node-int64');
const int64 = new Int64('0x1234567890abcdef');
const num = int64.toNumber();

Other packages similar to node-int64

bignum

The 'bignum' package provides arbitrary-precision arithmetic operations. It is more versatile than 'node-int64' as it can handle numbers of any size, but it might be slower for operations that only require 64-bit precision.

long

The 'long' package also deals with 64-bit integers and provides a rich set of arithmetic and comparison operations. It is similar to 'node-int64' but has a more extensive API for working with 64-bit integers.

bigint-buffer

The 'bigint-buffer' package is designed to work with Node.js's native BigInt type, providing buffer conversion utilities. It is a modern alternative to 'node-int64' that leverages the BigInt type introduced in newer versions of JavaScript.

README

JavaScript Numbers are represented as IEEE 754 double-precision floats. Unfortunately, this means they lose integer precision for values beyond +/- 2^^53. For projects that need to accurately handle 64-bit ints, such as node-thrift, a performant, Number-like class is needed. Int64 is that class.

Int64 instances look and feel much like JS-native Numbers. By way of example ...

// First, let's illustrate the problem ...
> (0x123456789).toString(16)
'123456789' // <- what we expect.
> (0x123456789abcdef0).toString(16)
'123456789abcdf00' // <- Ugh!  JS doesn't do big ints. :(

// So let's create a couple Int64s using the above values ...

// Require, of course
> Int64 = require('node-int64')

// x's value is what we expect (the decimal value of 0x123456789)
> x = new Int64(0x123456789)
[Int64 value:4886718345 octets:00 00 00 01 23 45 67 89]

// y's value is Infinity because it's outside the range of integer
// precision.  But that's okay - it's still useful because it's internal
// representation (octets) is what we passed in
> y = new Int64('123456789abcdef0')
[Int64 value:Infinity octets:12 34 56 78 9a bc de f0]

// Let's do some math.  Int64's behave like Numbers.  (Sorry, Int64 isn't
// for doing 64-bit integer arithmetic (yet) - it's just for carrying
// around int64 values
> x + 1
4886718346
> y + 1
Infinity

// Int64 string operations ...
> 'value: ' + x
'value: 4886718345'
> 'value: ' + y
'value: Infinity'
> x.toString(2)
'100100011010001010110011110001001'
> y.toString(2)
'Infinity'

// Use JS's isFinite() method to see if the Int64 value is in the
// integer-precise range of JS values
> isFinite(x)
true
> isFinite(y)
false

// Get an octet string representation.  (Yay, y is what we put in!)
> x.toOctetString()
'0000000123456789'
> y.toOctetString()
'123456789abcdef0'

// Finally, some other ways to create Int64s ...

// Pass hi/lo words
> new Int64(0x12345678, 0x9abcdef0)
[Int64 value:Infinity octets:12 34 56 78 9a bc de f0]

// Pass a Buffer
> new Int64(new Buffer([0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0]))
[Int64 value:Infinity octets:12 34 56 78 9a bc de f0]

// Pass a Buffer and offset
> new Int64(new Buffer([0,0,0,0,0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0]), 4)
[Int64 value:Infinity octets:12 34 56 78 9a bc de f0]

// Pull out into a buffer
> new Int64(new Buffer([0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0])).toBuffer()
<Buffer 12 34 56 78 9a bc de f0>

// Or copy into an existing one (at an offset)
> var buf = new Buffer(1024);
> new Int64(new Buffer([0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0])).copy(buf, 512);