bn-str-256

bn-str-256

A simple, functional library for big number math, with up to 120 digits of precision, more than suitable for working with 256-bit/32-byte numbers used in domains like blockchain.

What sets this apart from other big number libraries is a very simple functional syntax where most operations result in a decimal string (e.g., '412.959'), which, depending on your application, may be a more useful representation.

Additionally, all functions accept plain numbers, decimal strings, exponential strings (e.g., '1.5e-8'), hex (e.g., '0xf00b47'), binary (e.g., '0b10011'), or octal (e.g., '04471') encodings, as well as node Buffer objects as input. The library can likewise convert numbers to any of these encodings or Buffer objects.

This library is built as a wrapper around the awesome decimal.js-light library.

Installation

npm install bn-str-256
# or
yarn add bn-str-256

Examples

const bn = require('bn-str-256');

// Add two numbers.
bn.add(1234, '0x4953'); // '20005'
// Subtract two numbers.
bn.sub(1234, '1.5e-3'); // '1233.9985''
// Multiply two numbers.
bn.mul('1234.521', '305'); // output '376528.905'
// Divide two numbers.
bn.div(1234, '0x4953'); // '0.06573970486...'
// Take the modulo of two numbers.
bn.mod('1.412e8', 33); // '29'
// Raise to a power.
bn.pow(1234, 8); // '5376767751082385640407296'
// Take the 3rd root.
bn.pow(1234, 1/3); // '10.7260146688...'
// Remove decimals.
bn.int(44.4121); // '44'
// Round.
bn.round(44.68); // '45'
// Count decimal places.
bn.dp(44.312); // 3
// Count significant digits.
bn.dp(44.312); // 5
// Truncate decimal places.
bn.dp(44.312, 2); // '44.31'
// Truncate significant digits.
bn.dp(44.312, 3); // '44.3'
// Get the sign of a number.
bn.sign('-31.4121'); // -1
// Work with some big numbers
bn.sub('0x8ffffffffffffffffffffffffffffffffffffff',
 '1591029491249109201931039109512131121212') // '51380915346385064...'

// Compare numbers a variety of ways.
bn.cmp(1, 2); // -1
bn.gt(321, 321); // false
bn.gte(321, 321); // true
bn.lt(320, 321); // true
bn.lte(320, 321); // true

// Take the minimum of two values.
bn.min('1294.31221944', '5.421e6'); // '1294.31221944'
// Take the maximum of two values.
bn.min('1294.31221944', '5.421e6'); // '5421000'
// Clamp a value to within an interval.
bn.min('1600', '1294.31221944', '5.421e6'); // '1600'

// Just parse a hex value.
bn.parse('0x49121') // '299297'
// Just parse a binary value.
bn.parse('0b1001') // '9'
// Just parse a Buffer object.
bn.parse(Buffer.from('foo')); // 6713199

// Do some math and output a hex string.
bn.toHex(bn.mul('3043131212', '495')); // 0x15eb97423f4
// Left pad a hex string to 20 digits.
bn.toHex('4491959969129121', 20); // 0x0000000ff569ee4e22a1
// Convert to a buffer.
bn.toBuffer('99129129412'); // <Buffer 17 14 8e 79 c4>
// Convert to native javascript Number type.
bn.toNumber('0x491fc712d'); // 19629109549

// Split a number up into its parts.
bn.split('-34.99'); // { sign: '-', integer: '34', decimal: '99' }

All Functions

name (alias)	description
parse(x) (expand)	convert a Number, exponential string, hex/octal/binary-encoded string, or buffer object into a decimal string
add(a, b) (plus)	Add a and b
sub(a, b) (minus)	Subtract b from a
mul(a, b) (times)	Multiply a and b
div(a, b) (over)	Divide a over b
idiv(a, b)	Divide a by b and return the integer portion
mod(a, b)	a modulo b
pow(x, y) (raise)	Raise x to the y power
log(x) (ln)	Natural logarithm of x
log(x, base)	Logarithm of x with base y
int(x)	Return the integer portion of x (no rounding)
round(x)	Round x to an integer
sum(...args)	Sum all arguments
neg(x) (negate)	Negate x
abs(x)	Take the absolute value of x
sqrt(x)	Take the square root of x
exp(y)	Raise the mathematical constant e to y
max(a, b)	Take the maximum of a and b
min(a, b)	Take the minimum of a and b
clamp(x, l, h)	Clamp x to be within l and h, inclusive
sd(x)	Get the number of significant digits of x
sd(x, n)	Set the number of significant digits of x to n
dp(x)	Get the number of decimal places of x
dp(x, n)	Set the number of decimal places of x to n
sign(x)	Get the sign of x (-1 if x < 0, 1 otherwise)
cmp(a, b)	Compare a with b(where -1 if a < b, 0 if a == b, 1 if a > b)
eq(a, b)	Test if a == b
ne(a, b)	Test if a != b
gt(a, b)	Test if a > b
lt(a, b)	Test if a < b
gte(a, b)	Test if a >= b
lte(a, b)	Test if a <= b
toHex(x)	Convert x to a hex string (e.g., 0xf3abb)
toHex(x, length)	Convert x to a hex string and left truncate/pad it to length digits. If length is negative, the result will be right padded/truncated.
toOctal(x)	Convert x to an octal string (e.g., 04335)
toOctal(x, length)	Convert x to an octal string and left truncate/pad it to length digits. If length is negative, the result will be right padded/truncated.
toBinary(x)	Convert x to a binary string (e.g., 0b10111010)
toBinary(x, length)	Convert x to a binary string and left truncate/pad it to length digits. If length is negative, the result will be right padded/truncated.
toBuffer(x)	Convert x to a Buffer object
toBuffer(x, size)	Convert x to a Buffer object, and left truncate/pad it to size bytes. If size is negative, the result will be right padded/truncated.
toBits(x)	Convert x to an array of 1s and 0s representing its bits.
toBits(x, length)	Convert x to bit array and left truncate/pad it to length digits. If length is negative, the result will be right padded/truncated.
fromBits(bits)	Convert a bits array of 1s and 0s to a number
toNumber(x)	Convert x to a native Number type. Precision loss may occur.
E	The mathematical constant e (2.71828...)
PI	The mathematical constant π (3.1415926...)