catstodon/app/javascript/mastodon/utils/numbers.ts

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import type { ValueOf } from '../../types/util';
export const DECIMAL_UNITS = Object.freeze({
ONE: 1,
TEN: 10,
HUNDRED: 100,
THOUSAND: 1_000,
MILLION: 1_000_000,
BILLION: 1_000_000_000,
TRILLION: 1_000_000_000_000,
});
export type DecimalUnits = ValueOf<typeof DECIMAL_UNITS>;
const TEN_THOUSAND = DECIMAL_UNITS.THOUSAND * 10;
const TEN_MILLIONS = DECIMAL_UNITS.MILLION * 10;
/**
* @param {number} sourceNumber Number to convert to short number
* @returns {ShortNumber} Calculated short number
* @example
* shortNumber(5936);
* // => [5.936, 1000, 1]
*/
export type ShortNumber = [number, DecimalUnits, 0 | 1] // Array of: shorten number, unit of shorten number and maximum fraction digits
export function toShortNumber(sourceNumber: number): ShortNumber {
if (sourceNumber < DECIMAL_UNITS.THOUSAND) {
return [sourceNumber, DECIMAL_UNITS.ONE, 0];
} else if (sourceNumber < DECIMAL_UNITS.MILLION) {
return [
sourceNumber / DECIMAL_UNITS.THOUSAND,
DECIMAL_UNITS.THOUSAND,
sourceNumber < TEN_THOUSAND ? 1 : 0,
];
} else if (sourceNumber < DECIMAL_UNITS.BILLION) {
return [
sourceNumber / DECIMAL_UNITS.MILLION,
DECIMAL_UNITS.MILLION,
sourceNumber < TEN_MILLIONS ? 1 : 0,
];
} else if (sourceNumber < DECIMAL_UNITS.TRILLION) {
return [
sourceNumber / DECIMAL_UNITS.BILLION,
DECIMAL_UNITS.BILLION,
0,
];
}
return [sourceNumber, DECIMAL_UNITS.ONE, 0];
}
/**
* @param {number} sourceNumber Original number that is shortened
* @param {number} division The scale in which short number is displayed
* @returns {number} Number that can be used for plurals when short form used
* @example
* pluralReady(1793, DECIMAL_UNITS.THOUSAND)
* // => 1790
*/
export function pluralReady(sourceNumber: number, division: DecimalUnits): number {
if (division == null || division < DECIMAL_UNITS.HUNDRED) {
return sourceNumber;
}
const closestScale = division / DECIMAL_UNITS.TEN;
return Math.trunc(sourceNumber / closestScale) * closestScale;
}
export function roundTo10(num: number): number {
return Math.round(num * 0.1) / 0.1;
}