gristlabs_grist-core/app/common/NumberFormat.ts
Paul Fitzpatrick 5ef889addd (core) move home server into core
Summary: This moves enough server material into core to run a home server.  The data engine is not yet incorporated (though in manual testing it works when ported).

Test Plan: existing tests pass

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2552
2020-07-21 20:39:10 -04:00

77 lines
3.0 KiB
TypeScript

/**
* Here are the most relevant formats we want to support.
* -1234.56 Plain
* -1,234.56 Number (with separators)
* 12.34% Percent
* 1.23E3 Scientific
* $(1,234.56) Accounting
* (1,234.56) Financial
* -$1,234.56 Currency
*
* We implement a button-based UI, using one selector button to choose mode:
* none = NumMode undefined (plain number, no thousand separators)
* `$` = NumMode 'currency'
* `,` = NumMode 'decimal' (plain number, with thousand separators)
* `%` = NumMode 'percent'
* `Exp` = NumMode 'scientific'
* A second toggle button is `(-)` for Sign, to use parentheses rather than "-" for negative
* numbers. It is Ignored and disabled when mode is 'scientific'.
*/
import {clamp} from 'app/common/gutil';
// Options for number formatting.
export type NumMode = 'currency' | 'decimal' | 'percent' | 'scientific';
export type NumSign = 'parens';
// TODO: In the future, locale should be a value associated with the document or the user.
const defaultLocale = 'en-US';
// TODO: The currency to use for currency formatting could be made configurable.
const defaultCurrency = 'USD';
export interface NumberFormatOptions {
numMode?: NumMode;
numSign?: NumSign;
decimals?: number; // aka minimum fraction digits
maxDecimals?: number;
}
export function buildNumberFormat(options: NumberFormatOptions): Intl.NumberFormat {
const nfOptions: Intl.NumberFormatOptions = parseNumMode(options.numMode);
// numSign is implemented outside of Intl.NumberFormat since the latter's similar 'currencySign'
// option is not well-supported, and doesn't apply to non-currency formats.
if (options.decimals !== undefined) {
// Should be at least 0
nfOptions.minimumFractionDigits = clamp(Number(options.decimals), 0, 20);
}
// maximumFractionDigits must not be less than the minimum, so we need to know the minimum
// implied by numMode.
const tmp = new Intl.NumberFormat(defaultLocale, nfOptions).resolvedOptions();
if (options.maxDecimals !== undefined) {
// Should be at least 0 and at least minimumFractionDigits.
nfOptions.maximumFractionDigits = clamp(Number(options.maxDecimals), tmp.minimumFractionDigits || 0, 20);
} else if (!options.numMode) {
// For the default format, keep max digits at 10 as we had before.
nfOptions.maximumFractionDigits = clamp(10, tmp.minimumFractionDigits || 0, 20);
}
return new Intl.NumberFormat(defaultLocale, nfOptions);
}
function parseNumMode(numMode?: NumMode): Intl.NumberFormatOptions {
switch (numMode) {
case 'currency': return {style: 'currency', currency: defaultCurrency};
case 'decimal': return {useGrouping: true};
case 'percent': return {style: 'percent'};
// TODO 'notation' option (and therefore numMode 'scientific') works on recent Firefox and
// Chrome, not on Safari or Node 10.
case 'scientific': return {notation: 'scientific'} as Intl.NumberFormatOptions;
default: return {useGrouping: false};
}
}