@gigwork/precise
v0.2.0
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Precision based math operations
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@gigwork/precise
Precision based math operations, suitable for simple financial calculations.
Installation
# npm
npm install @gigwork/precise
# yarn
yarn add @gigwork/precise
# pnpm
pnpm add @gigwork/precise
Basic usage
// Calculate the price with tax
import { add, getScale, round } from '@gigwork/precise';
const cent = 0.01;
const price = 9.99;
const tax = '8.875%';
const precisePrice = add(price, tax); // => 10.8766125
round(precisePrice, getScale(cent)); // => 10.88
// Carousel
import { mod } from '@gigwork/precise';
const carousel = ['A', 'B', 'C', 'D', 'E'];
const initialIndex = 0;
const steps = -42;
carousel[mod(initialIndex + steps, carousel.length)]; // => 'D'
// Random numbers
import { random } from '@gigwork/precise';
const randomPrice = random(0, 100, 2); // => 33.76
const randomHue = random(0, 359, -1); // => 230
const headsOrTails = random(0, 1, 0); // => 1
// Average and sum
import { avg, sum, random } from '@gigwork/precise';
const prices = Array.from({ length: 10000 }, () => random(0, 100, 2));
avg(prices, 2); // => 50.01
sum(prices); // => 500998.81
Functions A-Z
add
Adds provided parseable numbers. If second operand is percentage, the function will apply this percentage to the first operand
Parameters
a
(number | string | bigint): The first parseable number.b
(number | string | bigint): The second parseable number.
Returns
(number): The sum of the two numbers.
Example
import { add } from '@gigwork/precise';
0.1 + 0.2; // => 0.30000000000000004
add(0.1, 0.2); // => 0.3
add(10, '20%'); // => 12
add('20%', '10'); // => 10.2
Note
This function will not coerce provided values to numbers:
add(0.1, true); // => NaN
add(null, 100); // => NaN
add([1], 2); // => NaN
approxEqual
Checks if two numbers are approximately equal within a given delta.
Parameters
a
(number): The first number to compare.b
(number): The second number to compare.delta
(number): The maximum difference betweena
andb
. Default is0
.
Returns
(boolean): Returns true
if the two numbers are approximately equal, otherwise false
.
Example
import { approxEqual } from '@gigwork/precise';
const threshold = 0.0001;
const interest = (1 + 1 / 25000) ** 25000;
approxEqual(interest, Math.E, threshold); // => true
avg
Calculates the average of array or iterable of parseable numbers. Returns 0
if array is empty.
Parameters
nums
(Iterable<number | string | bigint>): An array or iterable of parseable numbers.precision
(number): The number of decimal places to round the result to. Default is16
.
Returns
(number): The average of the numbers.
Example
import { avg } from '@gigwork/precise';
const numbers = [6.123, 4.2345, 0.354, 1.2345];
avg(numbers); // => 2.9865
avg(numbers, 2); // => 2.99
avg([]); // => 0
avg(); // => TypeError
Note
Strings are iterable, which may cause a confusion:
avg('123456789'); // => 5
ceil
Rounds number to a certain precision towards -Infinity. This function is a shorthand for round(number, precision, 'ceil')
.
Parameters
number
(number): The number to round.precision
(number): The number of decimal places to round the result to. Default is0
.
Returns
(number): The rounded number.
Example
import { ceil } from '@gigwork/precise';
ceil(1.234, 2); // => 1.24
ceil(1234, -2); // => 1300
divide
Divides the first parseable number by the second one with provided precision and configuration allowing or disallowing division by zero.
Parameters
a
(number | string | bigint): The first parseable number.b
(number | string | bigint): The second parseable number.precision
(number): The number of decimal places to round the result to. Default is16
.strict
(boolean): Iftrue
, throws an error when dividing by zero. Defaults totrue
.
Returns
(number): The result of the division.
Example
import { divide } from '@gigwork/precise';
divide(4, 2); // => 2
divide('100%', 3, 4); // => 0.3333
divide(10, 0, 16, false); // => Infinity
divide(10, 0); // => ArithmeticError
divide(10, -Infinity); // => 0
Notes
Any finite number divided by Infinity or -Infinity returns unsigned 0, which is inconsistent with the built-in division operator and IEEE 754 standard:
10 / -Infinity; // => -0 divide(10, -Infinity); // => 0
This function will not coerce provided values to numbers:
divide(0.1, true); // => NaN divide(null, 100); // => NaN divide([1], 2); // => NaN
floor
Rounds number to a certain precision towards Infinity. This function is a shorthand for round(number, precision, 'floor')
.
Parameters
number
(number): The number to round.precision
(number): The number of decimal places to round the result to. Default is0
.
Returns
(number): The rounded number.
Example
import { floor } from '@gigwork/precise';
floor(1.234, 2); // => 1.23
// Same as round(1.234, -2, 'floor');
floor(1234, -2); // => 1200
getScale
Calculates the scale of a number, i.e. the number of decimal places.
Parameters
number
(number): The number to calculate the scale of.
Returns
(number): The scale of the number.
Example
import { getScale } from '@gigwork/precise';
getScale(0.001); // => 3
getScale(1000); // => -3
getScale(0); // => 0
Note
Note that the scale is the opposite of the exponent in scientific notation:
getScale(1e-3); // => 3
getScale(1e3); // => -3
getUnit
Calculates the unit of the number, i.e. the smallest number that can be represented by the number within it's precision.
Parameters
number
(number): The number to calculate the unit of.
Returns
(number): The unit of the number.
Example
getUnit(12.347); // => 0.001
getUnit(2000); // => 1000
getUnit(2024); // => 1
mod
Calculates modulo of provided parseable numbers. Keep in mind that modulo is not the same as remainder, you can read about it here: Mod and Remainder are not the Same.
Parameters
a
(number | string | bigint): The dividend.b
(number | string | bigint): The divisor.
Returns
(number): The result of the modulo operation.
Example
import { mod } from '@gigwork/precise';
5 % 3; // => 2
mod(5, 3); // => 2
-5 % 3; // => -2
mod(-5, 3); // => 1
5 % -3; // => 2
mod(5, -3); // => -1
multiply
Multiplies two parseable numbers.
Parameters
a
(number | string | bigint): The first parseable number.b
(number | string | bigint): The second parseable number.
Returns
(number): The product of the two numbers.
Example
import { multiply } from '@gigwork/precise';
0.2 * 0.2; // => 0.04000000000000001
multiply(0.2, 0.2); // => 0.04
multiply(0.33, '3.3e-1'); // => 0.1089
multiply('33', '24%'); // => 7.92
Note
This function will not coerce provided values to numbers:
multiply(0.1, true); // => NaN
multiply(null, 100); // => NaN
multiply([1], 2); // => NaN
parseNumber
Parses a number-like value into a number with given precision and rounding mode.
Parameters
numberLike
(number | string | bigint): The value to parse.precision
(number): The number of decimal places to round the result to.mode
('round' | 'floor' | 'ceil'): The rounding mode to use. Default isround
.
Returns
(number): The parsed number.
Example
import { parseNumber } from '@gigwork/precise';
parseNumber('0.1'); // => 0.1
parseNumber('1.5%', 2); // => 0.02
parseNumber('1.5%', 2, 'floor'); // => 0.01
Note
This function will not coerce provided values to numbers:
parseNumber(false); // => NaN
parseNumber(null); // => NaN
parseNumber([1]); // => NaN
random
Generates a random number within a given range with provided precision.
Parameters
min
(number): The lower bound of the range. Default is0
.max
(number): The upper bound of the range. Default is1
.precision
(number): The number of decimal places to round the result to. Default is16
.
Returns
(number): The random number.
Example
import { random } from '@gigwork/precise';
random(); // => 0.1234567890123457
random(5, 10, 2); // => 7.12
random(-1, 1, 4); // => -0.3701
round
Rounds a number to a given precision and rounding mode.
Parameters
number
(number): The number to round.precision
(number): The number of decimal places to round the result to. Default is0
.mode
('round' | 'floor' | 'ceil'): The rounding mode to use. Default isround
.
Returns
(number): The rounded number.
Example
import { round } from '@gigwork/precise';
round(1.234); // => 1
round(1.234, 2); // => 1.23
round(1.234, 2, 'ceil'); // => 1.24
round(7654, -2); // => 7700
round(7654, -2, 'floor'); // => 7600
subtract
Subtracts the second parseable number from the first one. If second operand is percentage, the function will apply this percentage to the first operand.
Parameters
a
(number | string | bigint): The first parseable number.b
(number | string | bigint): The second parseable number.
Returns
(number): The difference between the two numbers.
Example
import { subtract } from '@gigwork/precise';
0.3 - 0.2; // => 0.09999999999999998
subtract(0.3, 0.2); // => 0.1
subtract(10, '20%'); // => 8
Note
This function will not coerce provided values to numbers:
subtract(0.1, true); // => NaN
subtract(null, 100); // => NaN
subtract([1], 2); // => NaN
sum
Calculates the sum of array or iterable of parseable numbers. Returns 0
if array is empty.
Parameters
nums
(Iterable<number | string | bigint>): An array or iterable of parseable numbers.
Returns
(number): The sum of the numbers.
Example
import { sum } from '@gigwork/precise';
const numbers = new Set([0.1, 0.2, 0.3]);
sum(numbers); // => 0.6
sum([]); // => 0
sum(); // => TypeError
Note
Strings are iterable, which may cause a confusion:
sum('123456789'); // => 45