31 lines
1 KiB
TypeScript
31 lines
1 KiB
TypeScript
/**
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* Shuffle.
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*
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* Return a new array containing the shuffled elements of the given array.
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*
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* The algorithm used is not the most efficient, but is effectively a one-liner
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* whilst being reasonably efficient. To each element we assign a random key,
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* then we sort by this key. Since the key is random, the sorted array will have
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* the original elements in a random order.
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*/
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export const shuffled = <T>(xs: T[]) =>
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xs
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.map((x) => [Math.random(), x])
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.sort()
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.map(([, x]) => x) as T[];
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/**
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* Return the first non-empty string from the given list of strings.
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*
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* This function is needed because the `a ?? b` idiom doesn't do what you'd
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* expect when a is "". Perhaps the behaviour is wrong, perhaps the expecation
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* is wrong; this function papers over the differences.
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*
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* If none of the strings are non-empty, or if there are no strings in the given
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* array, return undefined.
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*/
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export const firstNonEmpty = (ss: (string | undefined)[]) => {
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for (const s of ss) if (s && s.length > 0) return s;
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return undefined;
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};
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