forked from treehouse/mastodon
72 lines
1.9 KiB
JavaScript
72 lines
1.9 KiB
JavaScript
// @ts-check
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export const DECIMAL_UNITS = Object.freeze({
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ONE: 1,
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TEN: 10,
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HUNDRED: Math.pow(10, 2),
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THOUSAND: Math.pow(10, 3),
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MILLION: Math.pow(10, 6),
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BILLION: Math.pow(10, 9),
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TRILLION: Math.pow(10, 12),
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});
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const TEN_THOUSAND = DECIMAL_UNITS.THOUSAND * 10;
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const TEN_MILLIONS = DECIMAL_UNITS.MILLION * 10;
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/**
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* @typedef {[number, number, number]} ShortNumber
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* Array of: shorten number, unit of shorten number and maximum fraction digits
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*/
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/**
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* @param {number} sourceNumber Number to convert to short number
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* @returns {ShortNumber} Calculated short number
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* @example
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* shortNumber(5936);
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* // => [5.936, 1000, 1]
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*/
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export function toShortNumber(sourceNumber) {
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if (sourceNumber < DECIMAL_UNITS.THOUSAND) {
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return [sourceNumber, DECIMAL_UNITS.ONE, 0];
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} else if (sourceNumber < DECIMAL_UNITS.MILLION) {
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return [
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sourceNumber / DECIMAL_UNITS.THOUSAND,
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DECIMAL_UNITS.THOUSAND,
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sourceNumber < TEN_THOUSAND ? 1 : 0,
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];
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} else if (sourceNumber < DECIMAL_UNITS.BILLION) {
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return [
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sourceNumber / DECIMAL_UNITS.MILLION,
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DECIMAL_UNITS.MILLION,
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sourceNumber < TEN_MILLIONS ? 1 : 0,
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];
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} else if (sourceNumber < DECIMAL_UNITS.TRILLION) {
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return [
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sourceNumber / DECIMAL_UNITS.BILLION,
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DECIMAL_UNITS.BILLION,
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0,
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];
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}
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return [sourceNumber, DECIMAL_UNITS.ONE, 0];
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}
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/**
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* @param {number} sourceNumber Original number that is shortened
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* @param {number} division The scale in which short number is displayed
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* @returns {number} Number that can be used for plurals when short form used
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* @example
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* pluralReady(1793, DECIMAL_UNITS.THOUSAND)
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* // => 1790
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*/
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export function pluralReady(sourceNumber, division) {
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// eslint-disable-next-line eqeqeq
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if (division == null || division < DECIMAL_UNITS.HUNDRED) {
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return sourceNumber;
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}
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let closestScale = division / DECIMAL_UNITS.TEN;
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return Math.trunc(sourceNumber / closestScale) * closestScale;
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}
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