30 lines
709 B
Plaintext
30 lines
709 B
Plaintext
// @flow strict
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declare function flatMap<T, U>(
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list: $ReadOnlyArray<T>,
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fn: (item: T, index: number) => $ReadOnlyArray<U> | U,
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): Array<U>;
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// Workaround to make older Flow versions happy
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const flatMapMethod = (Array.prototype: any).flatMap;
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/* eslint-disable no-redeclare */
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// $FlowFixMe
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const flatMap = flatMapMethod
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? function(list, fn) {
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return flatMapMethod.call(list, fn);
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}
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: function(list, fn) {
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let result = [];
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for (const item of list) {
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const value = fn(item);
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if (Array.isArray(value)) {
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result = result.concat(value);
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} else {
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result.push(value);
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}
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}
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return result;
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};
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export default flatMap;
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