31 lines
1.9 KiB
JavaScript
31 lines
1.9 KiB
JavaScript
/**
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* formatCount — the ONE place the fleet decides how a COUNT is punctuated.
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*
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* ★ IT HOLDS en-US ON PURPOSE. Whether numerals follow the reader's locale is a DRIVER decision and
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* it is currently held, so this file changes nothing about what anyone sees: every caller renders
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* exactly the digits and separators it rendered before. What it changes is the number of places that
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* decision is written down — from thirteen call sites across four bundles to one.
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*
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* That is the whole value while the policy is held: if the answer becomes "follow the locale", this
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* is a one-line edit here (read the same hostLang -> getRuntimeLocale() -> detectLocale() chain the
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* text reads) instead of thirteen edits by four owners, each free to pick a different locale source.
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* The first divergence in that world would be invisible: two panels in one dashboard, same number,
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* different separators.
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*
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* ★ IT FORMATS. IT DOES NOT DECIDE WHAT EMPTY MEANS, and that distinction is not fastidiousness —
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* it is the bug this fold would otherwise have shipped. The three `fmt` helpers it replaced looked
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* interchangeable and were not:
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* DashboardDataTable null/undefined -> '' and '' falls through to Number('') === 0, so "0"
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* DashboardDetailDrawer null/undefined/'' -> '—'
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* useDashboardShell null/undefined -> '—' and '' likewise becomes "0"
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* Three different answers to "what does a missing count look like", in one dashboard. Folding them
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* onto one empty policy would have silently changed two of the three — a table cell going from blank
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* to an em dash, or an em dash appearing where a zero used to. So each caller keeps its own guard and
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* hands this function a value it has already decided is real.
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*/
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export const COUNT_LOCALE = 'en-US'
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/** @param {number|string} n a value the caller has already established is present */
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export const formatCount = (n) => Number(n).toLocaleString(COUNT_LOCALE)
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export default formatCount
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